straight pipe... or not to straight pipe..???

what I want to do is keep my cat back exhaust and straight pipe where the cats are....

I've heard SOOO many mixed reviews on this.

the main argument is that doing this well noticeably decrease low end Trq and maybe give you a 5 hp at the top ( this would not be worth it to me if this is the true case)

other side is saying absolutely do it especially with your OBD1 it gives you 10-15 whp and you dont lose any trq.

^ these were some of the responses from other forums.

interesting enough, 2 of my buddies whom both work as bmw mechanics say

1- DONT do it waste of money plus doesn't GIVE YOU anything.

2- while the other completely contradicts what he says- saying I will feel a huge difference....


any input will be great... kinda confused on this situation..

if im not mistaken the biggest difference comes with a tune...otherwise your not maximizing the new found increased flow from removing the cats

The real reason to not do it, is doing so is a Federal CRIME. Not just a fine, but you can serve jail time for it.

Is it worth that much to you?

High flow cats give little to no backpressure. Hot Rod Magazine did a test years ago and found high flow cats as good or even better than straight pipes.

I have a friend that straight piped his M3 and he dynoed it before and after and it gave him extra power ( i forgot the amount he has told me) not only that, but you also get that nice loud sound.

It's not illegal for non-op cars, but if you want to register the vehicle for use on public roads, yea I'm sure it's highly illegal.