BMW R1100GS/R1100R/R850R Catalytic Eliminator Exhaust Systems: To make installation simple the catalytic eliminator exhaust system includes an oxygen sensor bung to accept the fuel injection system?s oxygen sensor. Two different mounting options are available. A high mount system which retains the stock position of the canister or the low mount system which lowers the canister and allows the use of the BMW full size saddle bags. We do not offer CF or X-Metal CF canisters for the R1150RT due to the elevated exhaust temperatures produced by this bike.NOTE: "HM" part number are standard mount and "M" part numbers are low mount systems.