My combo I'm running will be in excess of 500 FWHP. Set of Doug's LT, x-pipe. On motor I should be 425-450 plus a 100+shot on occasion (undecided on size of shot) Will I sacrifice much power if I go to 2.5". Thanks.

 

I think its a must if your going with a single exhausr but if your going with duals i think 2.5 are enough

 

With that much power at the wheels, you need at least two three inch pipes. If you are staying with a single pipe look at least at the 4 inch. Otherwise you will have a serious restiction

 

Beat me to it...

 

500 FWHP as in flywheel/flexplate horsepower? Single 3.5" but a 4" wont hurt. Single 3" is really hurting that setup with nitrous IMO

Dual 2.5" is fine.

 

ok so my motor is a 383 with almost 500 hp at the flywheel and planing on over a 100 shot 3" y pipe and 3" from y pipe to muffler would be to restrictive

 

Heres a general outline that helped guide me to my choice. It's from dynomax's website.

 

I've always gone by Vizard's values of 115cfm per square inch of pipe and 2.2 cfm per hp.

single 3" is 7.07 sq. inches. It will support about 813 cfm of exhaust flow. Engine requires about 2.2-2.3 cfm per hp. That means a 3" single will support 369 hp before it becomes a restriction. Duals is good to 738.

Single 4" is good to 1445 cfm of exhaust flow or 657 hp
2.5" is only good to 257 hp for a single and 514hp for duals.

 

Really good info posted by Orr

 

thanks alot guys very good info