THE TECH

I've been debating now about which to do. I really only want to do one or the other. The longtubes and x-pipe are definitely more pricey and seem to cost a lot for the hp they provide.

Anyone have dyno info on before and after with cutouts installed?

jbondfl

Actually I think you'll find that longtubes are pretty high up on the list of hp/$$.

Cutouts will provide you very little hp and very much noise.

C5sRule

I have been contemplating the cutouts too, because I like the idea of a quiet ride until you want it loud.

THE TECH

Why would they provide little hp? If they dump either before or after the cats, they would eliminate any hp loss through the balance of the system.

My other main issue with the aftermarket longtubes is that most if not all will not bolt up to the stock cats. Aftermarket cats are no good since they are just as illegal as running no cats.

jbondfl

Keep reading on the forum and you'll see that real hp gains from the cat-back are in the 5-10 hp range and most are suspect. Most here will tell you that cat-back systems are for sound quality only, not performance.

Hp gains from longtubes are in the 25-40 range and solidly documented. The cat-back is NOT the most restrictive part of the exhaust, the manifolds are.

Read more, think it over, and do what you will. I don't have either one. I'm going strictly on what has been posted here before.

Good luck.

Cozmo

I used to have TPIS long tubes on my car. They eliminate the pre-cat a.k.a. the "pup" cat. They use the stock cats. See pic below. TPIS on the left, stock exhaust on the right.

I now have Kooks long tubes with high flow cats and no pre-cats. They are legal and passed emissions testing in Texas. CA is a lot tougher, so I don't know what systems would pass there.

THE TECH

Looks good. That could work for my application.

jhelms

Do the typical cutouts normally mount in the place of the cats?

CCA Corvette Parts

It torque you will lose if you mount them up there.

...no back pressure

Most I've seen mount after the H/X

Peace
Chip

WKMCD

It's a mute point. There is no room to mount cutouts before the cats. There's really no room until you get back to the transmission. I thought hi-flow cats were legal as long as they are in the stock location. I know they are in my state. Check with one of the Cali forum sponsors like Andy at A&A or Charlie at RPM.