ok so the 92 Si i bought has a test pipe in place of the cat. very cool, however i have to smog it {i live in arizona} so i can register it. i bought a new cat from autozone, and proceeded to replace the test pipe with the cat. upon removel of the test pipe, i noticed that there was 1 flat metal flange gasket on each end of the cat plus the round metal doughnut gaskets that go inside the flanges. i had the doughnut gaskets but not the flange gaskets. i went back to autozone and also to Schuks and neither could find a listing for these flange gaskets, either in theyre computers or theyre books, i even looked myself. i cannot reuse the old gaskets as they are junk. i think part of the problem might be that i have a DC sports 4-2-1 header and an APEXI exhaust, but they stock cat fits fine to these so im not sure if theyre should be a gasket problem. do you just use the doughnut gaskets? or do you need both types of gaskets together? and where the hell can i get these? please help i really wanna drive my new lude its been sitting for a week without plates

 

well the test pipe came with the right gaskets.

but your new cat might not have the right gaskets.

just go to kteller.com or your local exhaust shop. they should be able to help you.

irrc: aftermarket gaskets are highly sought after since they are harder to find

 

honestly im not sure if it was technically a "test pipe" because it had an O2 sensor bung with an old O2 sensor attached to it. it doesnt affect anything, in 92 the preludes o2 sensor was before the cat in the downpipe. its kinda weird, its almost like its a resonator. its shaped like a resonator, and it has the soundproofing inside it. but its the same length as the cat with the same flanges. does anyone have any experience with replacing cats on 4th gen preludes? im still not sure about those flat flange gaskets if they are supposed to be there or you just use the metal ring gaskets

 

yeah, i had the same one. it was an obx one.

the flat ones are usually for the cat hookups.

the ring gaskets, to my knowledge, were only to connect the header top piece to the bottom piece.