For those with JBA headers...

Do yours ever make a rattly or grumbling type noise at idle or low rpm? I just can't track down a noise I keep hearing, most of time it's at a low speed, such as going slow through a parking lot... or sometimes sitting at a light and the a/c causes the idle to change, I'll hear it. It does sort of seem like it comes from under the firewall area, but I just can't tell.

If I really romp on the throttle, it sounds really good from the exhaust, but this low rpm noise is driving me crazy.