Lookin for advice regarding metal grinding noise...

[Ramboson]

Hey everyone. Im driving an 07 GS automatic, and not to long ago experienced a sick grinding sound upon acceleration. Took it to my mechanic and it turned out to be a loose exhaust sheild. I had it removed since he told me i dont really need it. Its been about 2 months since, and now a similar noise has returned. This time its not as loud, and seems to happen when I accelerate from a stop, or when turning and giving it gas. The sound lasts for about two seconds, I dont feel a change in performace, but the sound is disturbing. Sounds like its coming from the right front tire area. I searched around the forums and Ive seen the following possible issues:

CV joint is wearing out
water pump
exhaust components grinding against something.

If anyone could clarify these issues and or offer any other suggestions it would be greatly appreciated.

[Ramboson]

Well I looked under the car, figured theres no use in checking the serious stuff, figured if it was serious the car wouldnt drive right. I started poking around and shaking the exhaust components. Turns out it was another exhaust shield. This time it was the one on top of the pipe leading out of the catalyc converter. It looks like the hole for the bolt rusted out, so the shield was vibrating against the pipe. I didnt feel like taking it out so i just secured it bak into place. Now the sound is gone for now at least.