Ok guys, I need your input. My ’91 accord OEM catback, or should I say original stock pipes and muffler setup finally gave up on me therefore I’m ready for an upgrade. I’m currently running on DC ceramic headers connected to everything stock. I understand it defeats the purpose of having the headers to begin with, but I’m low on cash and there’s no immediate need for new pipes and muffler until now. My original goal is to get a quiet and discreet setup, as close to stock as much as possible, but that’s a little difficult to achieve if I’m also considering performance. I’ve finally decided to go for Apexi WS2 since most of the postings here points me to that direction. Now I’m also upgrading my catalytic converter to a performance, straight thru type. Here is where my concern begins. I understand the concept of the straight thru design, exhaust gases moves freely without or less restriction, but will this pass the emission test? I simply don’t want to spend all this money for the setup that will prevent me from passing the emission test later on. If emission test is not an issue, which performance cat is decent to get? I’m a little pressed for time since July 4th weekend is coming and I definitely need to make a decision soon and get this ride going. I appreciate any replies. Thanking you all ahead of time for your input.

Most modern catalytic convertors are monolithic (straight shot) type. You wont find chambered designs till you get back into the late 80's. They flow pretty good. Don't know much about AM ones, but as long as it's a convertor, what can they do?

BTW I was, until recently a state certified emissions/safety inspector, so I can tell you without doubt it would have to pass in Missouri, I don't see where you'd have problems unless you live in California and buy one that isn't CARB certified.

Many thanks for the speedy reply jeffcoslacker. I just don’t want to pour all this money down the drain if I’m to revert back to stock cat.

My advice would be to keep the stock cat convertor, and go on ebay for a testpipe. Run the testpipe 364 days a year, toss on the cat when you need to get it inspected. The testpipe will be cheaper than the highflow, flow better, and only takes a bit to swap out. You could do this with a highflow as well, but personally I'd get the testpipe.

That's a good suggestion, only problem I could foresee is if there is a post-cat O2 sensor on your car, the PCM will probably set fault codes without a cat in place.

It would be emissions related faults, and wouldn't effect driveability, but you'd have to clear the codes before an emissions test or it will auto-fail.