Stage 1 cams are for unopened 2L & 2.5L n/a engines and also work extremely well in turbo enginesStage 2 cams work well in unopened Hot-Street 2L & 2.5L n/a enginesStage 3 cams are similar in duration to Stage 2 but require aftermarket pistons with deeper valve reliefs.Stage 4 cams for high compression street engines that have aftermarket pistons with deeper valve reliefsStage 5 cams are for racecars with 12:1 compression or higher
*** Stage 1 & 2 cams are can be run with the OEM valvesprings. Stage 3 through 5 require valvespring kit found here: SPORT CAMS Ti Retainer Valvespring Kit ***