What dia. exaust pipe for LS1?

[skeeters65]

Just wondering if you guys are using 2.5 or 3in and if there are problems with either..
It is a 69 Camaro LS1 with heads and Cam.. I am using S&P headers and want to use Flowmaster mufflers with NO cats..

Thanks

[Shawn MacAnanny]

I'm running Jegs universal x pipe kit in 3" with Hooker LTs. an x pipe will give you a nive probabaly 5-10rwhp 10-15rwtq gain.

[skeeters65]

Shawn,
Is your system 3" all the way back or does it go to 2.5 at the tailpipes??

Thanks

[CarlC]

If it's a mild build then 2-1/2" should work fine but you will need a smooth 3" - 2-1/2" cone transition. Flowmaster makes these as well.

I will also be running S&P headers, 3"-in/out X, Flowmaster cone reducers into Magnaflow 2-1/2" mufflers, 2-1/2" tailpipes. I had a similar setup on the previous engine and it seemed to work well.

[Shawn MacAnanny]

I'll be running side exits right before my rearwheels so i wont have tailpipes haha. You should be fine with reducing them to 2 1/2" pipe over the axels. I have a set of slip on header reducer cones with O2 bungs i got my my headers if ya need them. I'm running carbed and 3" so i ont need them.

[streetk14]

My LS motor is putting out over 600 hp through a 2.5" exhaust with an x-pipe an 1 3/4" Stainless Works long tube headers. A 3" system would probably be better for me, but I have limited room under the car for that.

For a H/C LS1, 2.5" should be more than fine.

Andy

[Nine Ball]

From my experience with these engines, you should only need a dual 2.5" exhaust system if you are pushing less than 500 at the rear wheels. Then a 3" dual system would be better.

Keep in mind that 4th gen f-bodies only run a dual 2.5 Y-pipe into a single 3" catback most of the time, and they easily put down 425-450 rwhp through a single 3" pipe.