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im am getting a new exhaust made soon...im debating how to do this...should i go from the exhaust manifold back deleting the first cat and only having 1 hi flow cat? should i get 2 inches or 2.25" exhaust? will there be a difference between them...i dont want it extremely loud however i do want it to be a lot louder than it is right now with just a muffler...do i need 2 cats to pass inspection? would i be able to put in 2 hi flow cats? thanks

If you have two cats, then the car is a 94+ model.

You can remove the first cat without having emissions problems. It's only a start-up cat and helps reduce emissions on cold starts. It IS a restriction to the exhaust flow, so removing it would net you a few extra ponies.

A 2 inch exhaust should be suffiecient for the 1.6. A dyno would be able to tell the difference, but the wise thing to do would be to start out with a smaller diameter.

thanks for ur help...but what if i want to get turbo or a super charger in the long run...would i need an exhaust bigger than 2"?

depends on your goals... 2.25" would be a fine minimum for turbo... it would be unneccesarry in the mean time.

the dohc model has 2 cats? what do they look like?

I have a picture of the 1st cat as I had some faulty exhaust valves and well there was a hole melted in it. So I just rodded it out and attached it back on. Exhaust is quite a bit louder now. I don't know how to post the pic as I have no website. Maybe someone can tell me.

If your going the route of removing the first cat you might wanna look into a probe header Conversion. Removing that cat can horridly ruin the exsaust veloctiy.


If you really are going to supercharge it you will want to go with the larger of the two sizes. If your not going ot be doing it for a few years then i owulndt go larger than 2in.

how can removing the first cat ruin velocity? how will it affect the performance of my car with 2 in pipes...would u suggest 2 hi flow cats?

if you gut your cat, it will disrupt the velocity. a straight pipe is best, but a high flow cat will work if you need to have them.

ok so is it ok to do this...

2 inch pipes from manifold back, replacing both cats with one hi flow cat positioned in the spot where the second cat is right now