I have an 06 enthusiast and this sound didnt start happening until one day when i was having my tires replaced and when the damn shop was backing my car out, the ripped my plastic undershroud off, but i caught them when i seen it rip and before they hit my exhaust on anything. the sound seems to be coming from either directly underneath the driver side, or around the left front tire, and sounds just like a wrench or something being slightly tapped on another piece of metal.

heres what ive gathered:
-it is NOT load dependent, and when i say that, i mean the car can be rolling in neutral and you can still hear it
-it stops happening after about 10 mph
-it is not constant. it only happens maybe 2-3 times every minutes if you're driving slow.
-It is not insanely loud, just loud enough to be heard

Ive got under the car and just kinda tugged on a few things but nothing seems to be loose. i havent checked everything tho.

anybody have this problem???

 

How exactly did they rip your plastic undershroud off? Just trying to understand what you mean. If they were backing the car out why would the undershroud be hit before the exhaust?

Just trying to picture it and think about what possibly could be causing this.

 

Hope they connected the sensor wires on the suspension, by the brake rotor guard.
Might want to pull the wheel and look for something hitting it... it can sound like a "ting"

 

They probably did hit the exhaust before you noticed what they were up to...now it's rubbing or has a broken mount.

 

Sounds like you need a new shop...
They prolly damaged the muffler bearings. That's exactly the sound you describe.
Good Luck.