Hi Guys

I have a 2003 ls1 5.7L from a gto, in a Nissan Patrol 4x4.
It has a 224/232@50 .580"in .591"exh lift -114lsa cam. 90mm Holley throttle body, a big fuel system and a 122Maggie
What size single exhaust system would you recomend and what brand of mufflers.

Regards
gouldy

 

You need long tubes and dual 3" pipes all the way back. Straight thru (corsa or magnaflow) mufflers would be ideal. If you have to live with stock ex manifolds and Y pipe to a single muffler, your muffler choice might not really matter that much.

 

Thanks old motorhead
I am restricted to a single system all the way from the stock manifolds into a Y pipe and then a single cat. The whole system from the cat to the end of the muffler is only about 6' long. I was thinking about a 4" single but Im unsure how it would compare to the usual 3" twin that most people use.

cheers
gouldy

 

Check out oval 4 and 5" tubing, may be an option.

Jim

 

Thanks Jim
I can fit a 4" single in no worries, but im not sure if it will be a bit to big.

Maybe a 3.5" would do the job? I have been told that with a 4" I would loose some low down torque and with 3.5" I would loose some top end but how much? I don't know.

Cheers
gouldy

 

You won't lose any low end due to a an exhaust system that flows better. If someone tells you that, you need to "factor" everything they tell you from this point forward. You don't need any "back pressure" if your rig is tuned right. The idea that "you need X amount of back pressure" is just plain bull sheet. Even if you did (which you don't), you'll have plenty with the stock manifolds and 2 into 1 "Y" pipe even with no muffler.

 

that person is wrong. you'll be fine with a 4", but its gonna be LOUD. ahaha.

 

Thanks for your replies guys
I found this on the performance trucks forum, it is very helpful.

http://www.mk5cortinaestate.co.uk/calculator5.php

Cheers
Gouldy