Low Fly'n 8

I've developed a new strange noise. It's very noticable at drive throughs when right up against a wall. Only when idleing at about 800 rpm, it's a vibration that sounds like a piece of thin metal rattling. If you just touch the gas it goes away, almost like at a certain pitch and then comes right back at 800 rpm. I have the Racing Beat cat back. It seems to be coming from the middle to rear of the car. The car is lowered, making it difficult to get under and poke around a red hot exhaust. Anybody had this problem? It really makes the car sound like a POS when ideling and is driving me crazy I did a search but could not really narrow anything down to this.
Thanks.

WHD

expo1

How long has the RB Exhaust been on? Sounds like an exhaust gasket issue, the middle one near the CAT.

Low Fly'n 8

The RB has been on for about 8 months. No problem except at idle.

NoTears316

Do you still have the stock midpipe installed? I had some rattling from under my car. I originally thought it was a loose heat shield, but when I got the 8 on a lift, I found that it was my cat.

Go48

Does the sound disappear when you depress the clutch pedal? If so every RX-8 ever produced has it. It's the main shaft in the transmission turning on it's bearings. Get used to it, 'cause there is no "fix".

Low Fly'n 8

Definately nothing to do with the clutch. I've got over 34,000 miles and am very familiar with all the typical noises. This one is different. It looks like I'm going to have to get her up on lift somehow to pinpoint it. Thanks for the help though.

Go48

Well, I wasn't implying that it was related to your clutch. Just asking if the noise is heard regardless if the clutch is engaged or not. I guess based on your reply that it happens regardless of clutch action.