Your SPORTSMAN 1000 S '55 2021 YM is limited to 60 km/h. The Electronic Control Unit (ECU) MCECUA21S1S95T will allow you to reach 90 HP and a maximum speed of 78 mph (126 km/h) which will allow you to perform during racing events. The 3 mode button will allow a stronger accelaration (in mode "performance" - good for starting the race) or a lighter accelaration (usefull in Trial situation - duo riding or renting activity)