i have found through my searching and what-not that my issue could be a timing belt, but this issue just came up after the car came out of the shop for EXHAUST work. when i step on the gas i get a squeaking... almost buzzing coming out of my muffler. it seems to maybe lag a little too, but im not sure. anybody who has had this issue any info would be much appreciated.

 

Could be just about anything. You need to take it back to them and say "hey man you messed up my car. Fix it"
Maybe they installed a "bubb rubb whistlin' whooer".... WHOO WHOOO
Or they could have damaged the catalytic converter
They could have left a bolt loose
Could be a piece of metal tapping
Could be a broken pipe
It could be your muffler belt needs to be changed out. that happens sometimes at around 20,000 miles. It's a simple fix unless you have one of the DOHB setups. Have them lube your muffler bearings and replace belts.

 

Is it hitting the rear axel?

 

well, you can rest assured it is not your timing belt. Once that belt starts making noise, it is TOO late.

I would get the car up on stands or ramps and carefully look around underneath. Grab the exhaust (when cold) and shake it .. shake it HARD to see if it hits anything.

 

if its a exhaust leak look for black carbon marks on the pipes