My Car Makes a Funny Noise
 

I don't know what is causing this so I thought I would see if anyone here has an idea. It's been going on for a while and doesn't seem to harm anything, but it sounds bad.

It sounds like a metalic scraping or vibrating noise, its just loud enough to pick up over all the other sounds. It's very unpleasant.

This only happens in a very narrow RPM band, from about 2800 to 3000, it also only happens at light throttle or under engine braking, even moderate acceleration will make it go away. It's hard to pinpoint where it's coming from, probably underneath the car, hard to say back or front, I mostly notice it when there is something on the side of the road that can reflect sound.

I suspect the exhaust, but I don't see any loose welds or anything like that, there are some small leaks further back (in my homemade exhaust), but this has developed after having that exhaust for quite a while. I use a begi mild steel DP, and the slip joint is wired together because the bolt never would fit, but again it has been like that for a long time.

I was considering cutting the muffler open and repacking it, but it seems like an extreme step for just a wild guess.

Any ideas?

Heat shields

Don't have any.

gremlins...