not going to happen from dodge on this one [all 04. 5's have cats] get a piece of 4" flex or have a truck exhaust shop make you up one 4" that is flared on both ends for 4"id both ends and use some band clamps... or cheaper way, just get some 4" straight pipe, and 2 4" butt joint band clamps [look similar to the lap joint clamps, but made for butt connections] and cut the cat out, and clamp the test pipe in...