NOS327

iTrader: (30)

Doing a heads/cam/intake/headers LS2 swap in my '67 chevelle. Probably have 100-125 n2o nozzle in it eventually too, so figure 500-ish at the tires. Will have true dual exhaust with x-pipe, hooker aerochambers, and tail pipes. 2.5" exhaust sufficient or do I need 3"?

thanks

joker machine

i would go with 3"

01boydws6

iTrader: (19)

you should be fine with 2.5" but if you have plans in the future to make more power than 600rwhp then I would go 3"

redtan

iTrader: (5)

First of all, I really hope you'll be making more than 500ish at the wheels on the juice. A h/c/i ls2 should be mid to high 400s right there...and with a 100 shot you should be close to 600 at the wheels.

Even without nitrous I think you will benefit from going 3". So with the shot you should definitely do 3", you will be leaving a good amount of power on the table at ~600rwhp with a 2.5".

NOS327

iTrader: (30)

It's a pretty conservative cam, but yeah I guess it ought to make a fair bit of steam. At lunch a guy pointed out that evolution is inevitable, so may as well go 3" and grow into it with future builds as well.

modstang60

3". Be future proof, it sucks going back and redoing a high dollar part

180ls1

iTrader: (4)

probably true

agenthol302

iTrader: (1)

3" easy

TurboStangJON

iTrader: (27)

I believe 3" is a standard in the LS world. I don't think they even sell aftermarket headers that are less than 3" but I may be wrong. In the end, 3" will be plenty and leave you tons of room to grow. Besides, 2.5 is for Mustangs!

sscamaroburn02

iTrader: (14)

3" for sure. thats a good amount of power with nitrous

BrdofPry

3'' hands down

redtan

iTrader: (5)

We're talking about exhaust here not headers. 3" is defnitely not the norm when it comes to exhaust size...2.5".

For headers you are right.

TurboStangJON

iTrader: (27)

I was just using the headers as a reference by saying I don't think they make a header with a 2.5" collector for an LSX. In turn, you would need to reduce the collector size and I don't think anyone wants to take a 3" collector and mate it to a 2.5" tube. Also, the norm for any person with his setup, heads/cam/nitrous LS2 is 3" and above exhaust size. Plus, I've looked on 4 different sponsors websites and every H-Pipe, X-Pipe, or Y-Pipe for these cars are 3".....thus making it the norm.

briancb1

Why are you going on a website and asking a bunch of people who dont know much about your car/setup to guess what exhaust you need?

Download PipeMax software, or if you cant locate it, go to www.speedtalk.com and ask somone who has it to run the program you need.

It tells you what primary size, primary length, collector size & length + the diameter of your tubing you'll need for your setup.

good luck