You just can't beat that Flowmaster sound, I would go with the 40 series just to keep it to a nice rumble, no need to have a stupid loud 6 cylinder. Do you have a lift? when I put mine on I went with a 44 series off road 2.5" output then got a piece of 2.5" pipe bent up to match the stock ultra restrictive pos and had to cut and bend it to clear the rear swaybar due to the drop brackets, it was kind of a pain but the end result was a good flowing exhaust that comes out in the stock location. I was debating having it dump out the side but I didn't want the exhaust coming out right under the door where my kids sit, and also I was worried about it getting crushed between the sub frame and a rock.
94 ZJ Limited- 7" IRO premium, 4.56 gears on Elockers and Chromo's, 35" claws on beadlocks, Kevin's sliders