i have flowmaster exhaust on my tj...and i went to get dual pipes out the back and there is not enough room for dual pipes in the back...there might be enough room in front of the rear tires but there is not enough room in the back...and by the way...a super 40 muffler will not sound good on your tj because it is a V8 muffler and it will not sound pleasing behind a 6 because it wont sound good on a engine smaller than V8...