Exhaust cut outs - worth the tuning work?

Ive had Max Wedge type cut outs for a few years...but gave up on using them at the track years ago because of the tuning demands going from street to track.

Im wondering what sort of improvement this type of mod would show if I persevered and decded to start using them again.

- Is the loss of back pressure a deal breaker for any performance gain?

- Is it worth the hassle with a 450hp motor/3500lb car?

- Im running fairly small mid pipes appx 2.5"... but the mufflers are Magaflos...again....is it worth changing my track tune?

I bought electric dumps for my Rampage.. I put muffs on that
were quiet enough that I didnt mind driving it but the back
pressure went up.. so now I use the dumps to lower the back
pressure... I'll open them at the track... these are 3" dumps
and a 3" exhaust with dynaflow muffs

I've always just ran my track tune on the street. What are you changing when you go from track to street?

I bought DMH electric Cutouts for the same reason Mike mentioned, I want to run a quiet fairly restrictive Exhaust system and have the ability to hit a button for more noise/power whenever I feel like it.

DMH

This is what I bought.. I hooked them both up to 1 switch
inside next to the shifter on the counsel
http://www.ebay.com/itm/Kylin-3-Electric...bca&vxp=mtr

I have used them on 3 cars. All picked up et w/ them. I used the simple weld in type. They take 5 minutes to remove and I don't have to jack the car up. They gave my mild 440 2.5-3 tenths over the closed exhaust (2.5" w/ headers) On this car they give me 1-1.5 tenths and a little over 1 mph. But this car has a much better exhaust system. I don't know what you mean by "tuning" as I run both the same.

With the right Exhaust system you shouldn't lose any ET. But if you want it to be quiet you may lose some.

That's how mine is, one momentary switch.
Should be fun!

Cut-outs have made a huge improvement on every car I have put them on. But there are no tuning differences. Light and part throttle are unaffected by them and why would you have them closed when opening the throttle? You don't have to open them all the way, just enough to let some of the pressure (and decibels) out.

In fact, I often have them cracked open a bit when going to car shows and such. Everyone looks as you pull in, but it is not so loud as to be obnoxious. The fun factor is even greater than the gain in performance for me and I have said here several times that I will never have another muscle car without cut-outs. Even if it is a mild build because they are a lot of fun.

This car is about as loud as I can stand... it sounds great at WOT but driving 51 miles (one way) to the track and back makes my head hurt.

I need to find a good spot in my exhaust to put some cutouts, I feel the full exhaust is holding my car back some considering it picked up a few mph with just a muffler change. Changing the mufflers also fixed the reversion and black intake manifold I had as well.

My driveway sucks so I have to be real careful about ground clearance, not sure I can squeeze any of those electric ones in there.

I have the motor section of the dumps pointed upward at about
a 30* angle just for road clearance... I did put the down spouts
on the outlet but I have them pointed inward so they arent a
clearance issue.. when I hit the track in a few weeks I'm gonna
do a open/close test just to see the difference in ET/MPH.. I expect
to see a decent difference... and I'm too lazy to pull the exhaust
off or even get under there to manually pull caps off... flip the
switch... done.. that works for me.. LOL

Wade Metzinger has a 68 Barracuda will a full 3" mandrel exhaust system. That car picks up 3 tenths with the exhaust off, so call it .25 for the weight difference of the system. I have a crappy 17 year old muffler shop bent 3" system that goes to 2.5 for the tails. I am sure its costing me something, how much I don't know but hope to find out soon.

I took off a couple tenths in the 1/8 mile using cutouts with a mild 440 and 2.5" mandrel-bent exhaust system.

I had a muffler shop make manual cutouts for me and splice them in. My 3" header collectors go to 3" cutouts, then after the cutouts it tapers down to 2.5" right before my 2.5" X pipe.

I don't tune any different for street or track.

I am going to install some cut outs as well. Does it make a difference where you install them? kinda like an X pipe would or header extensions?

I went from a 3.5" collector to a 3" cut out and 3" all the
way to the rear.. my muffs are 3" in and out and mounted at
the back bumper ... I installed the cut outs pretty close
to the collectors then the H-pipe after the cut outs.. I was
running out of room to put the H-pipe prior to the cut outs

If you have cut outs you can easily fab up a short flanged U to serve as an H pipe for normal driving or bridge an H pipe across it and either remove it or extend the blind flanges to the back of the H, you don't need much more than 5-6" of overall length so it doesn't add much at all in the way of weight.

I dont have any issue.. but I would have liked it before
the cut outs.. but it is what it is

I have used them for 20 years On a low comp car they gave me at least .2+ I find them easy to open and close and if conditions are right you can see up to .4 { but then again this cars exhaust is headers and a messed up system behind it

Anyone have an idea as to what a full exhaust system from headers to mufflers weighs?

I am guessing your thinking on the tune to fatten it up a tad with open exh. As for me I just run capped up all the time and leave everything the same at the track as how I drive on the street. I run a full exh system but I use a TTI mandrel bent X-pipe 3" system and the Ultra-Flow mufflers so I dont know if I would pick up much uncapped anyway. Ron

My old DartSport had a 3.5" X-pipe and 3.5" Magnaflow race mufflers. It was fairly quiet, people used to tell me they couldn't hear me pull into the staging lanes. The car would go 9.90 with the exhaust system and 9.90 with it removed from the car, didn't slow it down one bit, if it weren't for the 75 pounds it added, it would be a hair quicker through the exhaust.
If you're running small pipes and restrictive mufflers it's gonna slow down through the exhaust.


As far as the cutouts go, the very best way to mount them is to have the exhaust go 'straight' out the open cutouts, and have the street exhaust system branch off that, if that makes sense, I'll attach a photo.
I don't have room on my Duster to do it that way so my cutouts will be a couple feet after the collectors and the open cutouts will brach out the side. It will still sound good though and will let the pressure out.

Mine will be more like this....

Thx for the input

I asked about tuning because I found my mph dropped a little with open cut outs - I kind of assumed it was either a loss of back pressure or leaning out.

If improvement can be seen by using cut outs with a fatter tune....Ill give it another try.

My exhaust might be a little restrictive...my mufflers aren't.

I have found that MOST cases with open headers to exhaust
will need a different tune.. open will tend to be lean.. anything
you can do to help reduce back pressure will help... adjust the
tune for max MPH

back pressure is no friend to horse-power

I would think in many (if not, most) cases Capped Cut-outs themselves would ADD some backpressure to the system when they are closed for normal street operation . You are somewhat dead-heading a pressure wave back into the main flow stream. That why I think if you bridge an H pipe across them (instead of caps) you're adding system volume and reducing some Db levels at the same time.