I know i sound like a retard for asking; but would installing a high flow cat make my car fail emmissions?

 

no it will help it

 

It shouldn't unless it makes you throw a code.

 

well i changed downpipe which had a highflow cat and it threw a code

 

Sweet thx.

 

As long as you don't have a 2.2, you can turn off that code though by using HP tuners.

 

I've been looking at high flow cats, and I've noticed that there is two rather different types around. The first one appears to be just a cat and nothing else and the other is an entire manifold to catback assembly. After looking at the mounts for my cat i didn't see a way to install only a high flow cat without welding. The full assembly although 3 times the price look extremly easier to install, bolt off-bolt on. SO my question is how does one install the stand alone cat, and is the more expensive assembly worth the extra 200 bucks?