Question for people with high flow cat. Sound related.
 

I searched but could not find a similar experience....

Ok so I'm not new to the world of RX-8 with exhausts and such. I'm on my thrid RX-8 and it has the same exhaust setup as my previsou two. OBX exhaust and High flow cat.

The only change was I went with a RX7store cat vs. the RP Supercat I've used on the other the other two. So I just installed it and took it on a test drive. At about 4k rpms I get a woosh sound, almost sounds like a turbo spooling up to be honest. I use brand new OEM gaskets as usual and made sure all was tight. Rechecked after the drive. All was tight. I took it on the interstate and drove by the wall to get an echo, under 4k rpm under load there is ZERO sound of a leak but at 4k rpm I just get the loud woosh.

I'm not complaining. It doesn't sound bad. Just wondering if anyone else has experienced this. I'm thinking it's probably just how that cat/pipe sounds as the others I used didn't make this sound. It honestly sounds like a large turbo spooling or a large amount of air being pushed.

Answered my own question. It's the resonance chamber on my OBX exhaust killing the rasp. Turns it into a "whoosh" sound. Also I put about 30 miles on the car since and now that it's broken in some that noise has quieted down a lot. Kind of a shame, sounded cool.

btw, do you like the OBX? Even with the BHR resonator, with a hi flow cat and 3" midpipe, and damplifier soundproofing, my Greddy SP-2 wants to be on the edge of too loud.

Love the OBX. I've been a cheerleader for that exhaust on this site for years. I mean it IS an ebay exhaust but it's a decent quality one. It's a Fujitsubo knock off and sounds VERY close to it. The little resonance chamber really works. I still get a HINT of rasp with the new high flow cat but compared to other RX-8s I've heard with mid-pipes/high flow cats and other exhausts it's like night and day.

The OBX is fairly quiet though as exhausts go. Just a slight bit louder than stock, which is what I was looking for.

^Do you have a video or sound clip for that? I wanna get rid of my fart can noise from my AP midpipe.