This past weekend i changed the front lower mount and the mount on the passenger side. now, i have this intermittent exhaust leak that i really only hear when pulling off and around 3k rpms. it isn't terribly loud, but it's definitely noticeable to me. i took it to a muffler shop and they can't find the leak and it's not heard @ idle.

anyone have experience with this?

 

oh, and i'm using oem mounts.

 

You may have just shocked /cracked something loose when moving the motor around when you replaced the mounts.
You could replace all your exaust gaskets....but that will be a PITA.

Try another shop. Have the tech take a ride with you, let him hear the sound.
He will be able to find it. Also, in a few weeks you should also have a nice black carbon build up to show you the leak.