Alright I am just going to end up putting a cat converter back on my car. I have a Dia. of 2.5" , so what oem cat converter should I use? GSR? SI? I was thinking si but whats the stock Dia.? I don't want to get a high flow one because of the check engine light

 

and your car is??

 

I got a 99 ek hatch. Soon going to be supercharged. I got a skunk 2 cat back, ebay headers and test pipe. I need to put the cat back on because I tried all the SIM's for the 2nd O2 sensor but still dont work .

 

did you try the mechanical 02 simulator, it pulls the second 02 sensor out of the direct path of exhaust gases

anyway any 96-00 EX cat will fit check ebay

 

yea i did do ones of them with sparkk plug foulers. Did't work