There are limits but I've seen several of these Pypes Transverse systems on 10 second cars. There are quite a few of them in the FAST series as well running 10's and mid to upper 120's on F-bodies.
Yes my feeling is the Pypes race pro transverse flows better than the Dynomax. I've used the Dynomax too, but no testing with it. But I do like that muffler better for it's sound qualities.
I've also run the dual muffler system in 2 1/2" as I mentioned, it was no better than the Pypes transverse. Not at our HP level anyway. However if you go changing the pipe sizes you may find something. Only problem is though, on a 1st gen, and even a 2nd gen, the 3" stuff is a tight fit. It doesn't tuck up into the driveshaft tunnel very well, which in turn makes the mufflers hang even lower, plus the muffler cases are larger because of the larger pipe diameter, then snaking 3" pipe through the leaf springs back there becomes a challenge. They almost always create tire interference as well when it comes around the gas tank. Some aftermarket gas tanks are notched here just for this purpose.
The only kit I've used that I really liked in 3" for a 1st and 2nd gen is Torque Tech. It actually fit as well as could be expected, But they are no longer in business unfortunately.
My father runs something similar to what you describe on his GTO. He runs a 3 1/2" off the header collectors, and into a Dr. Gas "X" pipe that reduces the pipe to 3" coming out of the "X". That's the best way to reduce pipe size. Then he runs a typical 3" A-body system from there with race mufflers and tail pipes from Torque Tech. Actually a very quite system in the car, no drone.
I've done other similar things. For instance on our Z I run the Pypes transverse system but I wanted a stock appearance out the back so I substituted the tailpipes for factory 69 Z tail pipes in 2". Reduced coming out of the transverse muffler. Not only did this give me a factory appearance but it did a couple other things. It freed up a ton of room around the gas tank and leaf springs, it also allowed me to use the factory tail pipe hangers, and it also mellowed the sound of the Pypes system to a point where my wife is very happy with it. Yet it's highly doubtful the change cost any measurable HP because you're at the very end of the system where pipe size isn't critical, and it's only a short section of about 1 1/2 feet of pipe with very little bend in it.
There are tons of options depending on the sound level you want and how much work and money you can tolerate. But from my experience it's not worth spending the money if only chasing 5-10 hp. Unless you jump up in pipe size and want to deal with all those issues, then I think you'll find some gain. I have tons of sound clips with examples I've mentioned but it doesn't sound like that's what you're after.
|