On my previous 4Dr's I've had the AFE high tuck cat back, and Dynomax center exit exhausts. Neither seemed to give me any gains in performance(dynomax was a little loud for my taste.) On my current 2dr I went with an AFE axle back and I am very happy with it. Gave me the clearance I was looking for and isn't much louder than stock.
Here is the best picture I have, doesn't sit much lower than my VKS stubby rear bumper.