Rick, I got my 4" system from DD (Diesel Dynamics) and like it just fine. From my reading, the Jardine system from Nowel, Bill Kondolay, or Jannetty Racing seems to be favored for ease of installation and being a true "bolt-on" type system. Try some searches on Jardine or 4" exhaust (4"** exhaust) to get around the 4 letter work limitation.