Cat

[87vert30]

I have a 1987 E30 Vert, I'm new here, I was just wondering how loud would my car get if i get rid of the Cat and run an straight pipe. Will there be any HP gain? i'm also thinking about getting a Mark D chip....

Thanks

[xwill112x]

some say no, but i think so, when i removed mine, it revved up faster, and seemed to like the upper rpms more. just weld a pipe in place of the cat, and dont drive it til you get the chip installed, for maximum power gain effect. :)

[TexasTerp]

The MarkD will have the real affect. Removing the cat will open up air flow more and be much louder but you won't get a noticeable HP gain. It will be much louder, you need a solid muffler and possibly some glasspacks or resonators to calm it down.

[evil_twin]

Unless your car is a 'race car' there's not really a great reason to remove the cat.

[thereisnoyun]

I think the gains will be negligible unless the cat is completely clogged. If you need a new cat, just get a free flow magna flow and put it on.

[JasonC]

If the cat is good, take it off and sell it to a scrapper that will pay for that cat. Then just replace with a pipe. It will be louder, but not really that much. And you will hardly notice and change in power by your butt dyno. To get around MD inspection, put Historic tags on it.

[87vert30]

How do i know if the cat is good or bad? How much can i scrap it for? Sorry for the dumb questions, im new here....

[E30SPDFRK]

If you only want a sound difference remove the resonator instead. The cat actually does something besides quiet the exhaust, the resonator doesn't. Neither will get you any real horsepower, like 1-2hp max. Nothing you'll notice.

[bimmerpirate]

run straight pipes after the cat. the cat really doesnt do much to quiet it down. plus, getting rid of the cat will gain you nothing but less fuel economy.