About 18,000 miles ago, I installed a budget "Y" pipe which I have been very pleased with. 2 days ago I noticed a noise when driving between 1800 and 2400 RPMs. I thought, "This must be that 'bees in the can' problem several owners have experienced".
When I did a search about this problem someone mentioned checking the install to make sure no shields like the one on the oil pan are close to the exhaust. That could cause a vibration and a noise.
When I checked mine I found a bolt connecting a rubber insulator to the frame had come loose. I reinstalled the bolt and the noise is gone.
The moral of the story is to check your installation before thinking a noise is caused by the "Y" pipe.

 

and knowing is half the battle....

 

Did you notice it more in the morning when the car was still cold ?

 

G. I. Joe!

 

Yes, I did notice it more when it was cold.

 

I think that Im getting that problem now. So far I had no problems I wonder why now could it be because of the cold weather ?

 

I got a buzzing sound too, but it came (and still comes) from the FSTB... I don't have the tool to correctly tighten the actual bar that attaches to the end clamps... The end clamps were attached to the car with the appropriate torque, but the actual bar to the clamp was never tightened properly... I only notice this when it's cold also, but this shouldn't be your problem but check it anyways if you got a FSTB

 

hmm never got this

 

When the engine is cold the RPMs are higher and the vibration is probably noticed more.

 

That's true but when I start driving for a little while and I get up to higher RPM's I don't hear it no more.