I'm looking to get a hi-flow cat and will probably order the catco one for my ZC CRX Si. I have a DC Sports ceramic header and a Greddy SP exhaust. Which size diameter (2" or 2.25") cat do you guys recommend for this setup? Should I get the universal or direct fit one?

Thanks in advance for your replies.

 

Not to jack your thread but i would like to know if even getting a high-flow cat helps that much and if it will still pass emissions since PA is gay and we have to have them every year

 

I have a 2.5 test pipe yO! you can just swap it back to a cat when emmisions are needed. 5 whole bolts

 

Get a 2.25" high-flow and you should be good to go. The Greddy is 60mm, which is 2.36", but I don't know the collector size on the DC header...?

Alex

 

i have the CATCO hi flow one
works ok
i have passed 2 emissions with it and its like 2 yrs old
i have the 2.25", but IMO get a 2.5" exhaust and be done

 

thanks guys.

 

Here's my opinion. Get a cheap Hi Flow Cat like a Magnaflow Carsound Hi Flow Catalytic Converter, a 18" Magnaflow Resonator after it and then to your exhaust. The Muffler show will make all the welds necessary to fit it. Good luck, The High Flow cat just makes more ricey noise, something alot of people won't like. Just my .02 cents

 

I passed MD emissions with a DOHC ZC and Catco high flow.