I am not trying to stir the pot either, but it is worth noting that whatever the measurement is, It is indeed off. I did find it worth mentioning and if I still had the proof (I dumped all my old catalogs a few years ago), I certianly would scan it in. But none the less, it is an intersting topic indeed. And I am sure it actually covers more than just one manufacture.

Like I said before, nowadays researching before buying is always best.

Interesting post. I have had my DynoMax Super Turbos on for 11 years. I chassis dynoed them against open headers. We watched for drastic changes in the A/F, in between jetting and timing, it did not warrant racing it with the muff's off. It maybe time to get something on there a little more up to date, though. We'll see..

I talked to a guy who bought some 3" Super Turbos are few years back and he said he had the option to choose between 3" all the way through OR smaller internal pipes. He said back then they could be had both ways. Don't know if that is still true? I bet the 2 1/4" mufflers are 2 1/4" all the way through but who knows.

I drove my car around a few hours today. Its louder but not bad at all and no drone. One thing for sure, it idles better with the Ultra Flos. My cam has a 108 Lobe Separation Angle so I guess the exhaust gets out of the engine a little easier compared to the Super Turbos. But no doubt about it the idle is better.

Another thing I noticed is after the exhaust comes in, slams into the center-out pipe and squeezes around it, then the exhaust has to find its way into a straight cut internal pipe. And that flow director does not do anything. The exhaust just went above and below the center-out pipe and the flow director is not wide enough to catch the exhaust so wam into the side of the case and then into a smaller straight cut pipe. No wonder the car runs so much better now.

Now on the other end both internal pipes have tapered edges. It looks like the one pipe is put in backwards: tapered edge on exit and straight edge on the inlet side.

I have 2 street cars. One is a 360(9-1,224 hyd roller,LD340,650 holleyDP) 4 speed Challenger that runs Dyno-Max 2 1/2". Runs 12.50@110 thru the mufflers. The second car is a Volare with a blown 340 that runs Ultaflows. it runs 11.00@122 thru the mufflers. Both seem to do their intended job. The Challenger is fairly quiet,The Volare is NOT. I've never uncapped either one.
Doug

My dad's road runner has a healthy 440-6 w/ 3" exhaust. It originally had Ultraflows on it, but he thought they were too loud so I put on a pair of super turbos. Sounds good and he's happy, but now it is noticeably slower. Ran much better w/ the ultraflows.

A 20" case Super Turbo has 3 x 14" or 42" of baffled tubing compared to about 22" in an Ultraflow, actual backpressure within the muffler could be measured by putting a pressure gauge through the shell of the case....I'm willing to bet that on most motors you wouldn't see very much if any pressure reading until a 440" motor got up over 5000 rpm or so, and even higher with an X or H pipe on it. On a 416" stroker smallblock in a B or E body I doubt you would see any ET difference if you used a true 3" Hemi reverse flow and very little ET loss, maybe .05 or less in a 0-60 run even on a 500" high compression motor.

The Muscle Motors test of a 3800 pound very low 11 second approx 550 hp car saw .14 seconds and 1.29 mph in the 1/4 going from a rusted out 7 yr old 20" Hemi turbo to a 14" ultraflow back to back, but the DB's went up (from 93 to 100)substantially. And that was on slicks, so with most cars and on street tires I doubt the real world difference would be as noticable as the seat-of-the pants meter might indicate.

Obviously a perforated straight pipe is going to outflow a reverse flow of the same pipe od....My only issue with them is anybody can buy them and for every well-tuned nice sounding Mopar there's a more than a hundred "hey look at me!" Boy-racers who really just make a lot of noise

These days I think I'm more impressed every day with the FAST guys doing it (reasonably quietly) with 2 1/2" duals and manifolds. The best sounding mufflers to me are the Corsa's but they don't seem to do well with big overlap motors. To me on the street I/ve always prefered a more stealthy low deep rumble that allows you to hear the 'chirp' of the high compression roller motor over what pretty much a generic loud 'open header' cackle type sound which just reminds me of walking around the pits for 40 yrs. I don't mean that as a insult to glasspack style mufflers but us guys that have been around a while can tell you they could tell the difference between a Ford from a Mopar or Pontiac just by the tone....from a half a block away....and that all goes away with a glasspack...so for me I guess it's more a nostalgia thing I guess...and maybe that's worth a tenth or so . But opinions vary, I guess.

Being that we're all older than dirt around here, hopefully some will realize a "DYNOMAX SUPER TURBO" is nothing more than a 1960's Chevy Corvair Turbo muffler with 1. less packing to make it louder and 2. two little stamped "flow directors"?

And due to Walker/Dynomax's marketing genius, they have been able to sell them at triple the price of the original Corvair muffler since day one.

They do sound nice! And they are indeed slightly better than the original turbo muffler (or at least they used to be.....before they reduced the pipe sizes internally).

But they aren't a race muffler, and never were.
They are based on an OEM Chevrolet part, so it's not really fair to expect much from them.

You're right Zippy, Their popularity on the street was actually an unintended consequence...as anyone who has had a Turbocharger knows the snail knocks so much of the DB's and exhaust pulsation and reversion out of the system ( the turbine acts like a check-valve) that you need very little in terms of actual 'muffling'.

My point was that the reverse flow design is pretty good and even a big motor like a 500" is really only 250" motors worth of airflow on a dual exhaust system. A well designed 3" low restriction system doesn't cost you very much power and when it does it's mainly at WOT and at the top of the RPM range, 95% of the time on the street it never comes into play.

I tell a lot of people that for every 10th an exhaust system is allegedly costing their performance, I can find them 3 in tweaking their carb and ignition tuning, or by swapping them to the right intake manifold

I have run these for years.I have had the 20" case 2.5" hemi super turbos on my Polara for years.They sound great with the dr gas x-pipe in front of them.