Installed a 3" system from Kolac. Got the SS flowmaster CAT and Flowmaster muffler. The tailpipe comes in 2 parts, so if you have a lift you don't need to take the track bar off, but I don't have a lift.... Other than that it wasn't terrible to instal myself. I used clamps to get it so that it would pass inspection and I will have a friend help me weld it up when he has time. The sound is pretty decent. I wanted a quiet system and at low RPM it is very quiet. It does give a nice throaty growl at about 2k RPM when you get on it a bit, but then quiets right down for cruising.
Next is to install the Old Man Emu steering stiffener and replace the ball joints, upper and lower control arms, plugs, wires and cap.
Newby with first Jeep!