sowbelle

I am doing an ls1 t56 install into a 1971 chevelle. The engine is stock except for Hooker LT headers with 3 inch collecter.
I am looking to get the pypes exhaust kit either 2.5 or 3 inch. Advice or experience with either setup is appreciated.
Later after the car is all together and running, I may put cam,intake heads but for now it will stay like this except for a good tune.
Thanks in advance

ijimmy

2 1/2 inch kit is good for around 450 475 horse , put an h pipe in the system , 3 inch , is great for anything above that .If I were you ,id go with the 2 1/2 , pypes systems at 2 1/2 flow alot better than other's of the same size due to mandrel bent tubes , that said the 70 thru 72 chevelles have quiet a bit more room for a 3 inch system , compared to 64 thru 67 chevelles , I have done both , so 3 inch is not out of the question , you just need to be more precise with placement , use a few more hangers , double check clearance at ride height , and as allways work from the back to the front

bczee

iTrader: (12)

I have 2 1/2" on my Chevelle, which should be more than enough for a stock'ish engine.
My engine is stock with only a LS6 Cam, Intake and Headers. I am using 40's Flowmasters..

lownfast

iTrader: (4)

I started with 2.5 but now have 3in mandrel thru magnaflows. It was too quiet with 2.5 for me. It's still easy on the ears with a bit more rumble on the highway but screams when you get in it.

OutlawDrifter

iTrader: (9)

dual 2.5" with an x-pipe and a good set of high flow mufflers (hooker maxflow, dynomax ultraflow) will support your needs.

AnotherWs6

iTrader: (17)

2.5 is more than fine unless you plan on breathing on it heavy down the road.

Exidous

iTrader: (11)

Dual 3" ONLY if you want it loud and/or have big plans for power down the road (non-turbo).

Otherwise 2.5" for sure.