My exhaust has some apart towards the rear. What is the pipe diameter? And there seem to be two parts that both look like a muffler but the rear one has fallen off and there is really no increase in noise. Thanks

 

from the cat to the muffler it 2.5 inch afther the muffler it gose to 3 inchs any good highflow muffler will sound good with out changing anything but the muffler any muffler shop will probley do it for 300 to $400 depending on the shop you go to.