Maybe... but I'd also be inclined to think it might also reduce scavenge, which could hurt power under the curve. And it may also be that the airflow needs with the larger pipe affected the tune for those who lost power going bigger.

It almost never happens (with any mod) that you get true a/b one change results that are well documented, too often other factors are in play too.

I'd love to see a true a/b comparison with dyno results of JUST changing from 2.5 to 3 true dauls with the SAME design, and with the distance one each side to the x exactly the same.

Folks, please remember too... it's damn hard to get the X dead center and the exact same distance from the collectors on an F-body. X pipes work great when they are set up like that (as you can easily do on a Vette) but not so hot when you have to have the x unequal lengths from the ends of the collectors.

 

I went from stock manifolds, two cats, single pipe over axle to SLP muffler (274hp/306ta) and swapped to Pacesetter LT's and a 3" x-setup dumped in front of the axle (282hp/318tq) and it didn't seem to make as big a difference as I was hoping. I'm now running a rebuilt motor with a few more goodies and I know that the 3" is overkill. It does sound really good though and I will be very reluctant to get rid of it for fear it just wont sound as good (IMO) with something else.... hehe..

 

am i the only person here who thinks that a dumped exhaust with little ground clearance is just f*cking hack? i think its absolutely disgusting to see the exhaust hanging so low under the car and i personally think dumps sound like any other 5.0 mustang on the road, lots of motor work done or not....if you're gonna do it, do it right, i have a 2.5" td setup tucked up in the factory location with long tubes and its no problem at all, so i can't fathom what everyone elses problem is

 

well your definitely entitled your opinion.

-edit- removed pics and link... I have whored my setup out in other threads no need to do it here.

 

While this isn't exactly part of the debate (or I just didn't read it haha), but I think that 2.5" would sound a bit better than 3". That, and as mentioned, the aid in ground clearance.

EDIT: PS Why not an H-Pipe? Not as efficient, but it still helps equalize the pressure for better flow. My 86 Suburban I had one installed and I like how it sounded afterwards Hell, people even do mini H-Pipes before the Y-Pipe on stock exhaust just to help out every little bit. Being poor myself, it'd be something I'd do lol

 

X pipe with daul 2.5 inch exhaust was great with my LS1


I would never run a Y pipe setup, unless its a lowered daily driver...