It is recommended that new exhaust gaskets and a proper jet kit be installed when changing an exhaust system on a carbureted motorcycle. It is recommended that new exhaust gaskets and a Power Commander be installed when changing an exhaust system on a fuel-injected motorcycle. There is no warranty on exhaust pipes and mufflers with regard to any discoloration. Discoloration (blueing) is caused by tuning characteristics, i.e. cam timing, carburetor jetting, overheating, etc., and is not caused by defective manufacturing.