G8 Exhaust rattle/vibration - not DOD

[BP505]

I have a very annoying rattle/vibration coming from my exhaust area under the car. It is only present when feathering the throttle between 1000-1500 rpm, which unfortunately is the typical around town cruising speed. If I accelerate sharply it goes away, only to return once rpms fall back to 1000-1500. It is not DOD related as it happens with DOD active and de-active. Here's the strange part; once the car has been driven for about 15 minutes, it disappears. It's only present the first 10-15 minutes after start-up while the engine is cold. Any ideas what may be going on?

[wreckwriter]

Did you put spacers on your driveshaft tunnel brace when you installed the headers? if not, do so.

[BP505]

Local tuner did the install. I'll check. Thanks.

[bubblyjock]

Now correct me if I am wrong but does the Drive Shaft Tunnel Brace from BMR remedy the rattle if there is one?

[GeorgeInNePa]

Sometimes, the spacers alone won't do the job if the installer didn't do his.

;)

I had to loosen the joints in the exhaust and push up on the pipes, then re-tighten the clamps. The installer had left the pipe resting on the cross brace when they installed the headers.

[todds87ss]

My rattle (which I thought to be exhaust related) was a damn tranny electrical retainer on the passenger side, banging on the heat shield. A little prybar action...back in bidness.
Oh, and my rattle was worse in reverse (my poet verse)