Remus has the best know-how in sound design. The R1150GS, R850 and the R1100GS mutate to sport boxers in higher ranges of speed. Also Laser, BOS and Sebring are first choice in power and sound. For your R1100GS you can choose between the Remus revolution as slip on without catalyzer and the front muffler in aluminium or titanium. For the R850GS, R1150GS and R1150GS Adv. there is a Remus Revolution available as slip on front muffler without catalycer in aluminium, titanium or black stainless steel or slip on muffler. By Laser there is a duo-tech slip on system available for the R1150GS. Exactly matched to the Laser exhaust system a tuning chip for motronic for the R1150GS. For the R1100GS models Laser offers a duo tech slip on muffler without catalyzer in three coatings. Also for the R1100GS available is the tuning chip for motronic. BOS offers for the R850GS and the R1150GS an exhaust system slip on in either stainless steel or carbon. By Sebring you can choose for the R850GS, R1100GS, R1150GS & Adv. between a slip on twister with catalyzer or a slip on twister without catalyzer.The Sebring exhaust extension must be mounted on your BMW if you have a internal sound tube and in addition use cases. The exhaust extension protects case and indicator.