NotCrapple

it's very RPM specific, so i'm thinking it's a resonance issue. happens in any gear, including neutral.

i adjusted the stromung a bit this weekend, and put on the front-most hanger that was left off for some reason (actually they probably installed the exhaust and didn't realize that the hanger will only go in if you unbolt the exhaust again)....i'm guessing that would have gotten rid of any resonance issues i'd have if it was the exhaust.

any common heat shields or some similar crap i should check?

Turbo_Anarchy

Generally most noises like that are exhaust or exhaust heat sheild related. If it was after that may be why the hanger was left off. If the
exhaust is not isolated from the car really well
it will cause resonation. Make sure all the mounts are still pliable. If it is a heat sheild, or broken muffler you may be able to find it by going along the exhaust and hitting it
with your hand or a rubber mallet.

escargot

1337 H4X0R!!!111

NotCrapple

reread my post.

4Driver4

Also check the heatshield between the center pipe and driveshaft.