noise from flowmaster american thunder exhaust

I got a flowmaster american thunder exhaust. A friend recomended it and they are very pleased with it, as iam i. Except lately, aboutt 2 months after it being professionally installed, there id a noise coming from under my passenger seat, which is where my exhaust runs under the truck. It is a rattling noise that happens only when i accelerate slowly, and my rpm's are around 1700-1900. Right before it shifts. Then the noise goes away when i rev it or completely let off the gas. Any ideas? any help is apprieciated, cannot figure this out, thanks!

 

check the bolts, i have the same sound.

 

check the tail pipe near the rear of the leaf spring. mine is making contact there under light throttle and a right turn. fitment issue which cannot be adjusted.

 

Alll good suggestions......may I add 1 more?

Mine was found while the truck was cold.....smacked the cat shield and heard the same rattle....traced it to a pebble/rock inside the cat shield.

I also had the tail end of the pipe making contact with part of the rear frame iirc but it was only on bumps.

The small pebble/rock incident caused an annoying rattle at low rpm tho.

Get under the truck with a glove and start thumping on parts on the exhaust and trace the sound if possible.

Sometimes flowmasters do rust from the inside out tho.......hopefully that's not the case for you.

 

Check the bolts and ALL your clamps.

If your setup is strictly held together with clamps (out of the box) - things may have shifted over time and are 'settling in' (so to speak).

I had mine welded at the clamps after we installed it.

 

It shouldn't rust after only 2 months.

But I will agree with you..... Mine has rusted out (holes) at the muffler out feed pipes after 4 years. This week I'm getting it removed and going back to a stock setup.