If you changed the y pipe back on a stock lg4, what would be the expected hp gain? 5-10?


thanks,

I don't have an answer to your question, but wouldn't the stock manifolds be more of a restriction than the y-pipe?

the y-pipe back will give you extra ponies with an aftermarket system. A good idea would be to buy a catback first. And if you car has high miles the cat too. A y-pipe is usually bought with headers.

LG4 manifolds are hurting.