How much louder is the catless version of this midpipe over the oem cat? I'm excited I finally bought one

Depends on catback obviously^

Woops, I'm in the process of buying a rev8, I can't really tell by looking at different youtube clips due to mic differences, distance, etc..

^ Its true!

Just got in a Greddy SE exhaust... Ill finally do a RB Rev8 + BHR catless Midpipe video before I switch over to the Greddy SE... Ill post up some video when I get a new engine...

I've had the GReddy SE + BHR combo for over 2 years now..... it sounds great, mine is obviously a bit more muffled with teh turbo in there too but at wot high rpms it sounds fantastic, no raspiness....

I had greddy SE with the stock cat previous to going turbo and it is a similiar comparisson the loudness of that to my BHR MP + GReddy SE + turbo combo

just had my bhr midpipe installed today...sounds great outside the car but there is a horrible hissing sound while accelerating. I hope this isnt supposed to happen because it sounds awful...Any thoughts?

If it truly is "horrible", then you might have an exhaust leak.

Yes, the BHR pipe does have an "air rushing sound" at certain load ranges starting just before acceleration points, however it was fairly quiet and not intrusive at all. Far quieter than the exhaust volume out the back. If yours is intrusive, then there is probably an exhaust leak.

I mean it's a pretty noticeable hissing sound. I was driving with no music just listening to the sound and it sounds like a really large turbo spooling. like if you were outside the car and you heard the spool of a turbo, but i hear it inside.

so what's it mean if there's an exhaust leak?

chances are you tightened the bolts on one end, before tightening the bolts on the other end which is a common mistake. You need to make sure that the midpipe is properly aligned, and you do this by first slipping on the rear side to the flange of the catback, and slipping in the bolts that mate the front of the midpipe to the header. Start by tightening the bolts on the header side, but not all the way to spec. Now go back and start to tighten the rear side. This should help make sure that the midpipe properly aligns on both ends and reduces the chances of an exhaust leak.

I had it done professionally by a well respected shop so I dont think that's the problem but i suppose i can have them check it.

It shouldn't make any difference, not sure where people come up with that sort of thing

there is some slop in the header side flange and the bolts used to mount, so its possible to have a slight rotation in the midpipe. As strange as it sounds, I shot a note over to Ray when i first installed my MP because i was getting a weird buzzing noise that was coming from the header side. After spending some time making sure everything was tightened straight and aligned properly, noises went away. YMMV

I'm gonna call the shop tomorrow and ask them to inspect it. Didnt have time today but i'll keep everyone posted.

If you look around the site you will notice a lot of people have heard a hissing noise with this part. I think i saw it explained once as a result of the shape of the resonator.

I too am experiencing the noises as described in the last few pages. They appeared a day or so after I had my midpipe and after I did my initial review on my trouble shooting thread. The sound is almost unbearable at low rpms and taking off from idle. The first time it made the noise I jumped out of my car assuming my pipe was dragging on the ground - it sounds like someone threw metal shavings in my resonator or something. The noise tends to go away after some spirited driving I believe, but the initial pulling out of my driveway and the slow driving till I'm out of my neighborhood is embarrassing.

Hello, for what it's worth, I installed the BHR midpipe several days ago, and I here the hissing sound also.
I read some posts that say this is normal. No other noises though.
I was very happy with it, especially cause my cat was fried and now my 8 runs great.

This does NOT sound normal. It is NOT the "rushing air" sound that IS normal with the BHR pipe.

This sounds like you don't have it mounted securely, and only ones the pipe expands from heating up does it gain enough tension on the mounting hardware to stop the noise.

Did the cat go bad and you put the midpipe on to replace it? Could that be remnants of a bad cat? If so, remove the cat back portion and try to back flush (with compressed air if possible) or shaking/banging the pieces out.

I'll get it lifted up again tonight and try to remount it once again - I did replace the cat due to what I assumed was a failure but it seemed structurally intact upon examination. If nothing works I'll post a video of the sound tomorrow when I start her up to head to work. It is a scary sound, but with no power loss it isn't a apex seal flying around like one of my earlier thoughts.

Apex seals aren't easily ejected in a Renesis engine due to the side exhaust ports. They just spin/bounce around and around and do more internal damage than previous versions of rotary engines.

I recently installed the Moroso stainless steel spiral flow muffler in the resonator position on my custom race exhaust system and it doesn't hiss :dunno:

I'll get a clip of mine .. it also makes some weird noises from time to time.

Hello all, just for the record, the hiss of the pipe doesn't really bother me. I would prefer it not, but the fit, ease of installation, and overall sound more than make up for it ( plus NO CEL! knock on wood).