Dynomax Hemi Super Turbo's. I put them on my car and I lovvvveee them.

The more I talk to him the more I think he is concerned with wanting them very quiet. I think I am going to look into the imperial mufflers.

I think Accurate ltd sell a quiet performance muffler.Might check with them.

Here's the one I've been wanting to try:
http://www.summitracing.com/parts/WLK-17853/?rtype=10

It's 2 1/2" in, 2 1/4" out, 18" shell length. Lists to be a direct-fit for 68-76 Cadillacs, so it should flow pretty well if it was spec'd for that engine size.

The Walker 17000-series is their turbo-muffler product line.

$28 at Rock Auto, too!

HotRod Dave, if you want the best of both worlds, save your money and buy some of these. I can tell you all you need to know about them and how they work on my car.

Pac I agree on the 2.75, they're out there I'm sure but probably not near enough demand to have anybody have them readily available. I'd go with that if they were.

I understand what my coworker is saying about the volume but this is one of those instances in which I will not believe until I have it proven to me.

I agree with 360VIEW, Use 2 mufflers. Remember back in the day they used a muffler and a resonator to quiet things. Two mufflers will do something similar. Find a decent flowing type. I would also add a cross-over or x pipe to help quiet things as well.

FuryFan, I made the set on my 69 Cuda and they are quieter than stock when closed and as loud as Flowmasters when open. They have zero resonation when closed and they roar when open. They flow like stockers when closed and even though this is not anything to brag about, they pass as much air when open as the equivalent sized Flowmaster.

They are expensive but offer a person the way to have the best of both worlds. For sure, they are not drag racing mufflers, they were not meant to be. I did a lot of tricks inside of mine to bump the air flow up and the ones that Waldron sells are darn near as good, air-flow wise.

For our A- cars, the 18" cases will fit fine although you need to drop the nose down a tad to clear the 4" actuator needed. For Bs, you could use the 19" or 20" case size.

The sound levels depend upon engine of course but I saw around 9 to 10 dBa difference in many rpm levels on mine.

The first video is a true 1970 400 VOE GTO. The second is my car with the stocker VOE mufflers. Mine are louder than the VOE GTO versions. The set below in the photo is on a 1969 Cobra Jet 428 Torino.

http://www.youtube.com/watch?v=Mwov5Kp0SCE
http://www.youtube.com/watch?v=oX5i4_CQqb8&feature=related

Tom Hand

My question would be how well/long do the internal operating parts hold up due to possible carbon buildup,moisture etc ?

And that is a great question 62MaxWagon. I (and Waldron's do I believe) use a 304 st. st valve plate mating with 409 st. st. tubing. The dissimilar materials keeps the sticking from occurring; indeed, it did in 1969-1971 when the parts were all 409 st. st. Both of these stainless steels are resistant to rusting all the way away. St. st. 409 builds up a surface condition of light discoloration/oxidation that then tends to stay put.

With the new fuels we have, the issue is not like it used to be in 1970. Plus, none of us fire up the car and listen and then shut them off. Okay, so I do to show off the mufflers' sound but I have no worries about them sticking as know what I did to them internally. Most of us tend to drive the cars and evaporate the moisture from the mufflers more so then what people used to do when these cars were new and used for transportation. A small hole will help if you just start and then shut the engine off.

My mufflers are now going on 6 years old. The originals in 1970 lasted about two to four years max (I heard) but tended to stick and required you to tap the end now and then to break them free. The new generation versions do not.

The cool thing is they stay closed while they sit and when they open or close upon driver control, they chatter briefly while seating and unseating the valve. The videos may allow you to hear the very brief rattle. That comes from the plate being free to float on its shaft letting it always take the correct angle needed to seat. This slight chatter also tends to polish away anything that may be starting to build up and change the surface and cause sticking issues.

The actuator is the part than can wear out but it is outside and easy to replace. A few of the very early ones needed a modification to the rivet that held the arm on the rubber diaphragm but that part is well understood and the engineering change was instituted several years ago.

I have attached the original patent illustration. You can see how they worked originally. The changes we made simplified them and made them much better, longer lasting, louder when open, and quieter when closed. Plus they flow more exhaust gases when open, and the new materiel we used makes them virtually "forever" mufflers, not short lived ones like they were in 1969-1970.

Tom Hand

I have a 410" SB with Diamond W2 heads. 3" through the mufflers and 2 1/2" tail pipes. I have Dynomax super turbo 3" mufflers and 2 1/2" Ultra Flows in the tail pipe. It is quiet. Super Turbo's are not enough by themselves. If I had it to do over, I would use 2 1/2" all the way withg hemi super turbos and ultra flows. I also have TTI 1 7/8" primary header pipe. Rectangular port(big) W2's are a bust for a street machine ( no bottom end torque )

Looks like a great design and I may seriously consider a set as I need to re-do my exhaust system. Just curious as to why you chose to go with vacuum activation as opposed to an electric solenoid. Seems like there would be less potential trouble areas with the solenoid, and it would work better with cams that may not generate high enough, or consistent enough, vacuum.

I also have Walker "quiet flow" mufflers on my MP Magnum 360. I would say they are definetly as quiet as an OEM muffler. As far as flow, I can't tell. They are the only mufflers I have had on this engine. As mentioned by another member, quality is not all that good. It has only been a few months and I can already see some rust beginning at seams.

Madmatt,
Good comments Matt. Here is why they are made like they are. A solenoid would cost more than the actuator plus the wiring and switch is more complex and expensive. The vacuum requires really inexpensive tubing and is simple to hook up and easy to adapt to anything. The 4" actuator lets cars with as low as about 10 inches of vacuum at idle easily build up enough vacuum in the reservoir to pull and hold them open. The spring that holds them shut has some force but the 4" actuator has enough "guts" to yank them open.
Tom Hand

WOW! they real proud of those muffler!