I recent bought a 2008 harley davidson vrscdx (night rod special) w/ abs. It has a super trapp muffler system on it. It has the stock air filter on it with the top on. The bike is running to rich I believe(it is backfiring when I downshift). There are no discs on the back of muffler though. I do not believe the previous owner had this muffler set up correctly. There is a silver disc with the allen screws all around it. I can take it off but there are no discs behind it AND no closed end cap. The silver caps on the end are covered heavily in soot. It also looks like a screw on each of the mufflers broke off inside where you put them..how can I get them out and order replacements? I would love to have this muffler system run correctly while still sounding as loud as I can have it. I have tried to identify some numbers(maybe part numbers?) on the bottom of the muffler, it might help with which model this muffler is: 64813-07, 31807, VR1130\1250