depends on how far you want to go with power increases.....the QSC and STM Rage 3 are about equal as far as performance, tun-ability and strength and are a great upgrade over the OEM primary on stock or lightly modified engines. If you intend on running big mud tires, then a lot of people like the Rage 6 as it applies more clamping force on the belt and prevents it from slipping....if you intend on adding a turbo or other major upgrades, then you should consider the Rage 8.....it is all about how much you can afford to spend!