Hey guys. i recently installed a greddy sp elite cat back exhaust system on my 00 civic si. it already had greddy headers on it. now my question is, should i do something about my cat? the cat is still stock. i heard magan flow cats are best? any suggestions? thanks!

 

You could.. I put a test pipe on my car. It made it a bit louder. But I also ended up running into the P0420 code. IMO, I would just keep the stock cat. I wanted to go back to a stock cat. (My honda is totaled now)

 

Keep it stock

 

i have a megan resonated test pipe on my 00 ex and i love it. maybe a tad louder but using an angled o2 sensor adapter i have/had no cel. since i spun a rod bearing though ill probly take it off and put it in my hatch. and since its resonated you dont get that raspy riceboy sound.

 

High flow cats have never netted substantial gains, unless the inlet and outlets are larger diameters.
Magnaflows in particular have issues, and most of the time cannot pass emmisions inspections, expecially in california

 

Really, there is no reason to swap out a stock cat, i would leave it alone.

 

Unless you are F/I, just keep the stock one. Replacing it with a high flow will net you very little power gains, and removing it completely will sound terrible IMO, especially with a header and catback.

 

Keep it stock. You're making no where near enough power that restriction is even an issue.

 

i do not live in cali so emmissions isnt an issue. really i should just leave the stock cat on? i thought with the greddy headers to a stock cat would basically take the point of the headers away

 

Header. Only one.

The point of the header? Unless you have more than a header and cat-back done, there really is no point to the header other than bling, and noise. Seriously, those parts alone won't net you any noticeable power.

 

yeah its got aem v2 intake, aem fuel rail, aem fuel filters, and a "high performance fuel pump" as the previous owner told me.

 

Keep the stock cat for a DD.