on my cherokee i really liek the magnaflow high flow cat, and dynomax muffler combo.
sounds good when up to speed, but not obnoxious at idle.
high flow cats can be had on ebay pretty cheap
92 XJ 4.0 HO,AW4, NP242, 30" BFG AT, 1.75 spacer and ZJ coils, double cherokee leaf pack and 2 inch rough country shackles, 2.5 inch dnynomax exhaust, magnaflow cat, front hooks & rear hitch, gas skid, front skid, warn t-case skid, 99+ intake, bored TB
02 KJ Limited, 255 70 16s, front skid, LS/373 gears