After getting y-pipe and custom 2.5 inch exhaust, the stock cat seems pretty constrictive, not to mention worn out. What's the best replacement for this? Do emissions have to be at a certain level for autocross, does anyone know?
Thanks in advance.

 

In some states you can't legally remove the cat unless you can prove that it was faulty when you replaced it. Some states are very picky about that particular point too.

At any rate, I would think that any of the "high flow" cats would fit the bill. Every test I have seen shows them to work just as well as stock cats (meaning that they are burning off the same amount of pollutants) so passing any sniffer test shouldn't be a problem.

 

k, thanks. i just wasn't sure if those test pipes off of ebay are quality or not.