I would like to know if I buy a Full system DRD exhaust - this is the header and full silencer system - For a 2009 Model WR 450 F will I have the header over the oilfiterbolt problem ? Can I use the silencer part as a slipon only or is there parts missing when you buy a "slipon" only ? I presume the DRD header is thicker than the standard Yamaha header ? Does the DRD have a Clamp on the silencer part ? Does not look like it from the DRD site?