i have a kubota rtvx1100c i also had a rtv900 like both but really do like the 1100 with heat and air.. my question i go in to my old home stomping ground in western colo elevation around 7000 ft give or take a few depending on my location when i back there i get lot black smoke not real good power i giving some though to installing a after market trubo.. has you all installed any at your place and if so what sorta results did you get and ball park cost. the one thing that made a lot difference is i have the optional hand throttle so can keep it a throttle use foot for speed only and that makes a lot difference on hills well mountains..