NGK Lower Heat Iridium Spark Plugs for RZR Turbo / Turbo S / Pro XP / Turbo R / Pro SPolaris RZR Turbo Lower Heat Iridium Spark Plugs Fits all RZR Turbo models including Turbo S, Pro XP, Turbo R & Pro S Sold as a pair For 2016 models we step down 1 heat range in the spark plug which helps prevent unwanted detonation under higher boost pressures. 2017 and newer models come with lower heat plugs from the factory, but these are a superior replacement plug. They are not lower heat, but are a more robust spark plug meant to take the abuse.