ok , if you are posting in the 4th gen forum
you won't have a problem with the o2 (since its on the b-pipe connected to the header) unless you are a 96 prelude
i used to have a resonated obx "high flow cat" which is basically a resonated test pipe. its made of really thick metal, seems almost better made than the stock cat. fitment was perfect ( i put it on myself ) i added it in once i got greddy headers/ RSR exhaust with the resonated test pipe. sounded good.
i needed to pass emissions legally so i bought a random tech cat (really great cat) and installed it. sound is same, even butt dyno didn't feel any difference.
if you need a resonated test pipe (obx brand), well i have one
and it has an extra o2 bung as well. but you shouldn't need it.