To be honest (and the reason I added the converter after the fact), initially I ordered the exhaust from Quadratec because I wanted one without a converter and it's illegal for a muffler shop to remove one--thus I had to do it myself. I had the muffler shop cut me a piece of pipe 32" long and I clamped it in place of the converter. With this setup, the exhaust really had a good sound to it, the equivalent of a "turbo" muffler as mentioned previously. However, I couldn't stop the fumes from entering the cabin when the rear window was rolled up (and the door windows open, too), and after my girlfriend griped about it for 2 months, I decided to go back with a converter. Even with the compact, hi-flow converter, there is no exhaust sound anymore, and yes, there is a slight/moderate drop in power (not that my engine is a powerhouse anyway), but all-in-all it's okay because all of the smell disappeared. If I ever have an older jeep that I can leave the top off all the time, I will get rid of the converter, but if you have a top on, it's tough to get rid of that carbon monoxide and exhaust smell. I've done a lot of modifications to the engine, so it's hard to pinpoint any one thing, but I feel like the converter is an improvement over the stock one--if you can't find one locally, order one from Rusty's Offroad. Plus, it's half the size of the original converter.
Currently an '86 CJ-7 and a '77 CJ-7 Golden Eagle---#4 and 5 following a '01 Sahara, '90 Sahara, and '85 CJ-7....