1SikCoupe

i have a 93 si i bought a dc sports header and a apex exhaust now i need some advice should i go 2 inch pipe or 2.25 and should i get a hi flow cat or not?

thanks help is apretiated

1SikCoupe

anyone?

NoSpleeny

Go all out if you have the cash. Hi flow cats are expensive.

civicrydah

Hey,

The whole exhaust system should flow free and have no bottlenecks whatsoever. Biggest bottleneck is ur stock cat. A cat is one of the most overlooked parts when it comes to an exhaust system.

Considering you have a 93 si that makes 127 hp, I would recommend getting 2" piping. This will cause you to have very minimal backpressure compared to a 2 1/4" pipe. I've got a 2 1/4" pipe on my sir. Anything bigger and that would result in backpressure.

I emphasize that it ur exhaust is a "system" cuz it has to work together. Your collector, piping, cat, and muffler should all be 2" in diameter.

A good hi flow cat that i recommend to anyone would be a hi flow carsound cat. It outflows any of the other cats on the market and produces the most cfm. It doesn't result in any hp losses compared to a testpipe or no cat at all. Its a must for an exhaust system.

Good luck and i hope that helps

imported_toyman29

go for 2'.. w/ the header + exaust.. n e thing bigger will just loose your torque like crazy..
2.25 is the max, if you really think 2.25 will give u power

your already gonna lose torque b/c the loss of back pressure.. so its your decision of balance on the torque/hp gains/loss

EL_Sport

If your stock cat is working fine, I wouldn't bother replacing it until you need to. You won't gain much if anything at all on an N/A car even with a header and catback exhaust. If you are looking for a high flow cat for your car, I have a slightly used Magnaflow (Carsound) cat if you're interested. jdm_rice@hotmail.com