Straight Through Type Mufflers On Street

Here's what they sound like:

http://www.youtube.com/watch?v=174t0pIdc6c&feature=player_detailpage

Initially I had 2.5" head pipes, UltraFlows and 2.25" tails. Way too loud. You couldn't hear someone next to you speak. Added an h-pipe and it was much quiter. Sounded like the old muscle cars. I changed headers and also changed to an x-pipe. Even quiter than the H, but definitely changed the tone. I like the latest setup best. I do have a video of this too if you want to hear it.
I'll bet you will need a crossover or multiple muffs to make it tolerable.

""I'll bet you will need a crossover or multiple muffs to make it tolerable.""

I thought of the largest straight through muffler in the rear (6 dia. x 14"/18"), then possibly the 4" dia x 18"/22" or so for a resonator, but I did not think of adding a possible crossover pipe. I am currently running each exhaust side seperately from each other. I will take some measurements to see what x-pipe might fit, just in case.

Thanks

Has anyone tried the chambered exhaust? I am curious what they sound like for a 340. They come in different sizes and lengths.

So they weren't horrible and cheap sounding?

I ran 3-1/2" Dynomax Race Bullets and they sounded like open headers. Tried the larger case welded (straight through) mufflers and I could still set off car alarms at idle. Sounded like a bunch of loud motorcycles. Finally git the 3" TTI exhaust with large Dynomax Turbo mufflers that come with the TTI kit. There seemed to be no change in performance, but now the car was much quieter.

Drone = Flowcrappers!!

I ran 2.5" HOOKER Aero Chambers on my 340-6 in my 81 Shorty for years. It sounded great and got lots of good compliments on the sound.

I run a full exh out to the rear bumper and its a 3" TTI system with an X-pipe and Ultra-Flow mufflers. You can here it in this clip as its not to bad at all to me. I can listen to my radio with no problem cruising along. Since I race my car I wanted a good flowing straight thru muffler and the Ultra-Flows are very good mufflers for performance. Ron

http://www.youtube.com/watch?v=bYIM2HLaOI4

Thanks for the replies and videos. Mine is a stock 340 I always liked the sounds of the 69 z-28s and 375 horse 396s that had them when new. It had a very crisp sound, I'm not sure the solid lifters had had a lot to do with it. I will try them , thanks again.

I have figured out that I want to run the TTi 2.5" X-pipe dual exhaust (with muffler eliminator pipes in place of where you would order mufflers under the rear seats) bolted onto my existing TTi headers/2.5" collectors. This gets me from my existing 2.5" collectors all the way to the rear bumper and I can add the Accurate SS 2.5" R/T tips. Then I can measure the straight section of pipe beside the gas tank and see which length of muffler would best fit the area.

I am thinking that If I use the X-pipe, I might be able to get away with the Magnaflow 6" diameter SS mufflers (14" or 18" long) beside the gas tank (in place of the existing OE style 7" x 18" mufflers). Then if this is still too loud for street driving, then add the Magnaflow 4" diameter SS mufflers under the rear seat (acting resonator)where TTi places the muffler eliminator pipes (18.5" long).

This should give me the straight through 2.5" exhaust and quiet it down for the street while using SS mufflers and SS R/T tips.

Thanks for all of the replies.

The TTI exhaust uses a offset inlet / center outlet muffler, so your elimination tube will have to be offset or angled for the tail pipes to be in the correct location. If you have a stock gas tank there is not alot of room for mufflers on the sides of the tank.

The elimination tube is TTi's design. They just call them ""2.5" x 18.5" MUFFLER ELIMINATOR PIPES w/ ID SWAGE ENDS"". So the exhaust should bolt up just like their muffler was in place.

My current OE mufflers are 7" diameter and they have offset-inside/center 2-1/4" pipes with the stock R/T tips. I am using them as a reference and I have take dimensions from the center line of those mufflers to the frame and the tank. Referencing their online pictures for Ebody tail pipes (attached) and knowing that other members have welded in 4" diameter mufflers in the stock position, I am hoping to stuff as big of a muffler in there as possible both diameter and length. I think a 6" diameter will work but if not, then Magnaflow makes a 5" diameter too.
Once I have the TTi muffler elimination 2.5" exhaust in place (with the R/T tips installed), that should show me exactly the muffler space required. Then is it just calling up my local Oreillys and having them order me a set of that size.
If the noise is too much for my streeter, then that muffler elimination tube just might get a shorter 4" muffler mounted to it to help as a resonator.

Thanks for your reply.

Y07_A66:

I recently added Magnaflow 7" round X 14" case mufflers (3" pipes) behind the axle to my 70 Cuda. I do not have the Cuda cutout valence, so with the turn downs the mufflers need to be positioned a little lower, and are slightly visible from the rear of the car. The exhaust work was custom bend, but I was surprised by how much room there is, at least for a 14" case. If I had the cutout valence, I believe everything would have tucked up very nicely, and I might have been able to run an even longer case.

I run these. http://pypesexhaust.com/i-13475154-race-pro-muffler-14-3-off-center-304ss-mvr19s.html

Dave,
Thank you very much for the picture. That is the first picture that I have found showing the MF round mufflers beside the tank.
I am surprised that you were able fit a 7x14 in there! Once I have my exhaust purchased and installed, I will cram the largest one in there because I am hoping to not have to use a resonator under the seat.

Do you have another angle of the 7x14 in there? How close is it to the bend on the over-axle pipe?
Have you tried your exhaust with only the round mufflers?
If not, is it loud now with the set of MF's on both sides?

Thanks allot!!

I'm late to the party here, but why don't you want mufflers under the car and only at the back?

I do not want mufflers under the rear seat due to ground clearance. We have speed bumps around our area and I don't want to have to worry about them.
I know the factory did this and my car used to have the resonators under the rear seat. But I want to see if I can put a large enough round muffler (thru style) beside the tank without having to add the resonator/muffler under the seat. This is why I will go with the x-pipe to see if that helps bring down the noise too. Worse case and it is too loud, then I will add a 3.5/4" round muffler under the seat.

Y07_A66:

The few photos I have right now are from the rear of the car. I hope to get the car out this weekend, and can snap a few other pics from showing the area between the axle and the tank.

Prior to adding the round MFs, only the oval Ultraflows were present. Everyone's view of "loud" seems to be different to me, and as you know there are many factors that will affect the sound level. My car has full 3", an X-pipe, headers, 400/470, and cam of [Email]248@050.[/Email] My tolerance has gotten lower as I have gotten older, and originally I felt the car was "loud" (as in the family knowing I was home before I even pulled into the driveway). Even now, you can hear it while idling in the driveway while inside the house. You have smaller pipes, less displacement, and less camming so you might be OK, depending on your tolerance. A straight thru muff isn't very quiet in my opinion!

The additional of the MFs did reduce the noise by about 10dB at some frequencies in some positions. My car was actually loudest by the rear wheel wells. Do you have a smart phone? If so, look for the "FrequenSee" app. I'll attach some before and after plots so you can see the impact. Here is the difference from the driver's side. First pic is UF only, second is UF + MF.

This is after the additional of the MagnaFlows. Driver side sound level. Notice that I picked up some low freq drone around 230KHz (or looked at differently, I didn't get much improvement in the sound level at that frequency after the change, but the frequencies around it did see a lot of reduction).

This is with UF only, 8 ft behind the car.

This is UF + MF, 8 ft behind car.

I should point out that the frequency response of the microphone on my wife's smart phone really falls off below 100Hz, so you need to be careful to not read too much into the really low frequency energy if you try this. I actually picked up a noticeable drone, only at idle in gear with the UF+MF. It doesn't even show on a plot, but my ear doesn't lie! As soon as I crack the throttle it goes away though.

For my Cuda, I bought my exhaust components from Accurate Exhaust Products LTD and it uses both a "Muffler" and a Resonator that look stock. Both are pretty much straight through and there is a low rumble for sure in the interior but the tone at idle and driving is very nice. I would make a recording of it, but I am not sure it would capture the sound very good. Inside the car, you can talk to a passenger at cruise but you do have to speak up a little bit.

Here is a photo of the two components together and with the E-Body I would not worry about bumps at all. The exhaust hangers in an E-Body keep the exhaust locked in pretty tight.

I also have a photo of the inside of the muffler if you are interested as it shows the very slight bend!

Dave,
I have not tried that app but I have tried a decibel app. Thank you for posting the information.

I have heard different things from different people about the loudness of the straight thru type mufflers. It does seem to matter on the size of the engine and the pipe size like you pointed out. This is why I am thinking of running two round mufflers on each pipe with the x-pipe.

My current OE 2-1/4" type mufflers (no resonators) are at least 12 years old and they are probably burnt/rusted out some over the years. They are fairly loud at idle and quiet at cruise and loud again at WOT. My phone app showed 88-91 decibels at idle from standing around the rear tires and working my way back to the bumper just above the tips. I can't imagine that the phone app is real accurate but it does give me a reference if I do swap out this exhaust this Summer.

Steve,
I have checked out the Accurate websight and I believe that those are 2-1/4" inlet/outlet with 2" tips. NOTE: The stock OE style mufflers are very restrictive (apx 175cfm). The straight thru 2.5" type are in the 500cfm range, but they are louder.

I do like their Magnum straight thru stock looking mufflers but they are a little too pricey for 2-1/4" inlet/outlet and I was told that resonators would be required with the Magnums to keep the noise down.

I am looking at a full 2.5" system from my existing TTi headers back to 2.5" tips. TTi does sell the 2.5" system all the way back and since they designed the headers, then my expectations are that the 2.5 exhaust should bolt up with little to no mounting issues. The exhaust is not my worry, it is the unknown loudness of the straight thru mufflers that I am worried about. I may have to change my plan before I purchase the parts but until then, I need to decide or find out how loud a pair of the round 6"/7" mufflers would be by themselves or with a pair of 3.5"/4" round mufflers (10-12" long max length) are with them.

Thanks for the replies.

Yes (about the Accurate Exhaust) The headpipes are 2.5 up to the resonator and they are stainless.

The Frequensee app looks pretty cool. Downloaded it and going to test it to see how it compares.

All:

I realized I posted the wrong images yesterday, and have corrected them. As I noted after adding the round mufflers by the tank I picked up some drone at idle. I actually took a third step by wrapping the UF under the floor boards, and it reduced the drone. Here is the result by the drivers side rear wheel well after the wrap. Basically I discovered that a fair amount of sound emanates from the muffler case itself, at least with the straight thru design.

Y07_A66:

Why are you considering adding round mufflers under the floor boards? If you need the extra sound reduction, wouldn't an oval give you better ground clearance, and allow a bigger volume muffler to be placed there? That would in essence mimic the factory setup, albeit with straight thru mufflers.

Steve,

I agree sound recording are not very good both at comparison and for letting someone else judge the results of a specific system. That's why I used the FrequenSee app for comparison purposes. It really helped me assess the changes in sound levels after each change, at least within the mostly flat portion of the microphone frequency response (which I would judge is about 100-12000KHz).

""Why are you considering adding round mufflers under the floor boards? If you need the extra sound reduction, wouldn't an oval give you better ground clearance, and allow a bigger volume muffler to be placed there?""

Dave,
I agree with what you are saying about the oval mufflers, but my thinking was that I would not find an oval muffler that was thin enough, so that is why I was guessing a 4" round muffler.
But, I found an oval muffler made by Magnaflow (#11226) that is 4" thick which is also a straight thru type of muffler (offset/center). I may still need to add round 6"-7" mufflers beside the tank to keep the noise down, but the oval straight thru muffler should help allot on noise reduction while keeping an open exhaust.

I may end up with a setup close to what you have, except both mufflers will be the Magnaflow's and 2.5" pipe.

Note: The above MF muffler will fit the TTi non-muffler design with one minor change. The OA length of this muffler is 2" longer than the Super Turbo part #17733 that TTi references. I would just have to cut off 2" off of the X-pipe length at the muffler end.

Ref: Dynomax: 2.5" #17733 (TTi option) 4-1/4" x 9-3/4" x 14" body. Per Dynomax: 410cfm (186hp)
Magnaflow: 2.5" #11226 4" x 9" x 14" body. Per MF: 530cfm (232hp) per muffler. (these are unrestricted numbers per the manufacturer)
2.5" exhaust pipe: 509cfm

Thanks again for your help Dave.

It appears that I will be looking at an oval and a round straight thru muffler per side. This setup will give me a 2.5" "straight thru" exhaust setup that includes a x-pipe (TTi non-muffler exhaust kit) and 2.5" stainless R/T tips (Accurate). This should be as quiet as it will get for a 2.5" straight thru exhaust setup.

Personally, I'd run some sort of mufflers ahead of the rear axle, then go up & over, then a pair of straight-throughs (6" dia. x 18" long) between the frame rail & the gas tank on an E-Body. I like the expansion chamber in a couple of places in a full exhaust like that. About the thinnest oval mufflers you will find with 2.5" internals is going to be 4-1/4" thick - pretty standard.

Y07_A66:

Not sure if you still wanted to see the axle side of the round mufflers, but here are a few. A couple of comments. Custom bend pipes allows the bends to go all the way to mating with the muffler, which helps reduce overall length. With slip-fit connections, there needs to be a few inch long straight portion for mating which makes the overall muffler length longer. There is a little over a finger width between the over-axle pipe and the shock. My mufflers are hung a little low to allow the turn down to get under the rear valence without pointing directly at the ground (which I did not want).

Closer view of pipe to muffler connection.

Clearance to gas tank.

Turn down area.

Dave,
Thank you again for your pictures. Nice job getting the 3" exhaust to work in those areas especially with the 7" muffler!!

I wanted to bring this thread back and get some more replies. I had planned on replacing my existing exhaust system this past year but other things came up. So, I am going to try and replace it this coming Winter.

I already have the TTi SB headers + 2.5" reducers. I am currently running tru-duals back to the original 6.2" diameter mufflers (18" case length, 2.25" pipe) and then thru the stock 2" R/T tips.
My plan is to remove the existing pipe, mufflers, and tips and buy the TTi 2.5" X-pipe assembly but with the Muffler Delete pipes (under the seats) that they sell. I want to add my own flavor of mufflers to the system and try to keep as wide open of an exhaust that I can. I will then buy the aftermarket SS R/T 2.5" exhaust tips.

After discussing this in detail with Magnaflow, my goal is to have a DEEP sounding exhaust at idle and at a cruise. I also want to use their 530cfm free flowing series of mufflers (Not the XL series which is a very restrictive 3 chamber design).
Note: My existing 6.25" x 18" case OE style mufflers are about 175cfm each.
I also want to keep the sound down so that I don't piss off the neighbors or the police and I want to only use rear mounted mufflers.
After searching through several muffler brands, sizes and shapes, and after many emails with the Magnaflow tech, I decided on a set of round MF mufflers that will mount in the "area" of the OE mufflers. I had a few choices of mufflers and I gave these to the tech to try and get some idea about the loudness of these mufflers. I first considered the front mounted mufflers, then I considered mounting both front and rear, and now I am leaning towards the rear mounted mufflers only. This is the reference that he gave me for noise:


""On a scale of 1 (stock) - 10 (straight pipes) I would rank the mufflers as follows (530cfm):

A) front mufflers only - 5/6 (#11226 = 4" x 9" x 14")
B) Rear mufflers only - 8 (#12866 = 5" dia. x 14")
C) Both front/rear mufflers - 2/3
D) Rear mufflers 6" dia. x 14" - 5/6 (#12616)
E) rear mufflers 6" dia. x 18" - 4/5 (#12646)
You may get a fair amount of drone with just the rear small round mufflers.""


My existing 6.25" OE mufflers are at least 13 years old and they are worn out, but no drone from idle to WOT. They are pretty darn loud at WOT. I consider them to be quiet at idle and at cruise and I think that they are too quiet. So from the above reference, I am aiming for the middle of the road for loudness and I am leaning towards the rear mounted 6" diameter x 14" long mufflers mounted beside the tank.
Once I get the TTI X-pipe, muffler delete pipes, and R/T tips installed, I will know exactly how much room I have to mount these mufflers. The OE muffler exits are offset towards the bottom, and the MF are straight through. All this means is that the MF muffler will hang down lower at the exhaust tip. But since this muffler is 6" shorter than the OE, I plan on moving the MG muffler towards the front of the car a few inches so that the muffler "may" not be seen when looking at the rear of the car. Plus if this 14" muffler is too loud, I can go for the 6" x 18" muffler and still have some room.
I am hoping that the combination of the 2.5" pipe, X-pipe, and the full length exhaust will keep the overall loudness down enough so that I don't have to buy the 18" mufflers or worse case, buy a set of oval mufflers to mount under the seats. I won't have all of my parts until mid-Winter, so I still have some time to think it through.

If anyone new has mounted their 2.5" mufflers beside the tank on their B or E bodies this past season, please feel free to give your opinions.
Thanks again to Davenc for all of the db references on his 3" system!



Thanks to all.

http://www.accurateltd.com/E-body_c_102.html

have a look there you might find exactly the mufflers you are looking for there

I don't believe that Accurate sells the 2.5" round mufflers. They do sell the 2.25" straight thru (Magnum direct bolt in to OE, 2.25") mufflers, but they are not the 2.5". Their repro mufflers are the 2.25" OE style that are very restrictive and I have that style currently on the car.

Thanks for your reply.

EDIT:
I am currently looking for opinions on if the X-pipe/2.5"/6" diameter muffler x 14" long setup is going to create a deep sound, too loud, not loud enough if this is possible. If no one has this setup, then I will continue to guess at what length/diameter of mufflers that I will need and just try it out.

Thanks again for the reading and the replies.

Has anyone mounted the Dynomax Ultra-Flow Rounds to the rear beside the gas tank? I found this 2.5" (6" dia x 14" case).
http://www.dynomax.com/ultra-flo-welded-round-centered-centered-596.html

Thanks

I finally got around purchasing the 2.5" TTi X-pipe and tail pipes for my Challenger. I then decided on the Hooker Max Flow mufflers. I have read many threads on these mufflers and they all suggest that they are LOUD at WOT. Some of the tests show that they flow 521cfm each and the decibal reading at WOT is 120+, which is the same as a 2.5" straight pipe. Due to this, I wanted to add resonators beside the tank to try an lower the WOT sound a bit but I want to keep the exhaust as straight through as possible for a street car. I do not want to attract the wrong kind of attention and I do not want to wake up my neighbors, so a resonator is a must.

Mounting Resonators to the TTi Challenger tail pipes:

TTi told me that they do not make their tail pipes for resonators, but with the help of Eric from Classic Chambered Exhaust, he has helped me come up with a resonator that will fit onto the TTi tail pipes.
Most of the aftermarket resonators that I looked at had 2.5" ID bushings on both ends which will allow them to slide onto the outside of a 2.5" pipe. But, since there is only about 16-18" between the centerline of the muffler mounting bracket and forward before the tail pipe makes the upward bend to the axle, I needed a resonator that has a front bushing with 2.5" OD to allow the Accurate R/T exhaust tip to fit in this area. So Eric made me a set of resonators that have the 2.5" ID bushing on the entrance side to allow the resonator to slip over the TTi tail pipe, and he has added a 2.5" OD bushing on the exit end of the resonator to allow the Accurate R/T tip to slip over the end of the resonator. Mounting the exhaust tip onto the end of the resonator makes the assembly shorter and easier to fit into this area beside the gas tank. The resonator that Eric made is #25-RES-SPE. It is a 2.5" through pipe with a 4" OD x 12" body size. The bushings extend beyond the case by 2.5" per end. This is the first "off-the-shelf resonator" that I have found that will fit into this area for my 70 Challengers with R/T tips and TTi tail pipes.
I could not have STUFFED a longer resonator into this area! But this combination fit perfectly into the area beside the Challenger gas tank. There is plenty of room to go larger on the diameter of the resonator in this area, but no more room on the length.
Thanks to Eric at Classic Chambered Exhaust! Excellent customer service!!

The previous picture shows the TTi tail pipe installed with the Accurate R/T exhaust tip. I removed the TTI mounting bracket and made my own bracket that uses the U-Bolt bracket for mounting the exhaust tip. Now I have room for a resonator.

This picture shows the Classic Chambered Resonator #25-RES-SPE mounted to the R/T tip. Easy install!

This picture shows that I could not have stuffed any longer "off-the-shelf" resonator into this area beside the tank.
There is plenty of room to add a larger diameter resonator since the original muffler was 6.5" in diameter, but there is no more length without modifying the exhaust tip or the resonator.

I always run cheap glass packs (bullets) in the tail pipes on all my cars that have louder mufflers. But that is to control the drone. I haven't noticed much sound reduction, though.

Drone was one of my concerns too with the straight thru muffler. But due to Winter, I still have a few months before I can take it for a test drive. Since I had the time, I found a way to add them now when it is more convenient.

The Challenger does not have a lot of room to just bolt in a standard 12" resonator. I could have gone longer if I removed the bushings and welded them in, but my goal was to make it removable in the case that I wanted to go with a larger diameter unit later on.

It appears that The Cudas seem to have even less space in this area than the Challengers.

I was able to take the car out today for the first drive since installing the exhaust over the Winter. Absolutely no drone from idle up to 70mph with the new system!
(TTi headers & 2.5" x-pipe, Max Flows/2.5" TTi tail pipes, CCE 4" x 12" resonators/2.5" SS R/T tips)

The sound is LOW and deep at idle. The cruising sound was not as loud as I was expecting. It has a nice base to it and it got loud quick during light to medium accel. I was not able to test WOT today due to the cool outside temps and tweaking the cruising A/F readings. I can't wait to test WOT!

I like the combination of the Hooker Max Flows and the Classic Chambered resonators!!

Anyone ever seen these?

http://portermufflers.com/

I run Summits 3 inch stainless ovals.They exit by the rear wheel and are just mellow.might as well say straight thru but not loud.Plus they look great and the price was cheap.Rocky