Look up Matt Walter and his third gen. He's running like 10.20's these days in a n/a LS manual trans 90's Camaro.
I've been friends with him on Facebook for some time and ffollowing his cars progress. 4th gen interior as well. He has fender exits.
BangShift.com ls manual transmission
Imo, the best part is all the ground clearance you'll gain and the ability to lower your car more and not have the exhaust hitting everything all the time when you daily drive it. I've asked him about how loud it was compared to under the car and he told me it wasn't that bad at all.
Soo, imo, the benefits outweigh the negative effects. You can even still run a little bullet muffler right before the fender if you want.