Odd noise!

[MERCMAN]

Ok, have heard a noise, tough to describe, but I would have to say it sounds like a metal guard of some type rattling at WOT, doesn't do it all the time, no rhyme or reason. Recently removed the silencer and replaced it with rubber cover as in the silencer removal thread.
Had service tech ride along, he heard it as well, says he believes it is something vibrating such as a guard or shield. Definitely not in the engine(so he says).
Next oil change he will get under the car and check for any loose guards/shields.

If I had to describe the noise, would have to say it was similar to the noise one used to get on the older cars from the metal tube that extended down from the air cleaner into the exhaust manifold when the tube was loose.

Comments? suggestions?

BTW the silencer thing might just be a "red-herring"
No decrease in performance noted when it happens,,
car has 5,000 miles

[Petrograde]

hmmm,... I haven't heard that noise,.. but,.. when I start the car in the morning I usually hear a weird 'thump' sometimes two thumps. I can't pin down where it's coming from,... front? back? ??????

Tom

[TripleTransAm]

The whole drivetrain torques to one side under load... could be a matter of some exhaust component touching the underbody when this happens. You have an early build date Marauder... recall the "low-VIN" Marauder being auctioned on eBay that has a service history including 'exhaust adjustments'... could be the same thing.

While they're looking around under the car, they should check for a faulty catalytic converter or two, by banging on the surfaces of the cats and listening for internal rattling... although I'd be inclined to think the rattling would be audible at low RPMs as well (as it was on my GTA when its cat gave up the ghost in 1996).