GSC Power-Division billet S1 cams for the Mitsubishi Evo X are designed for those with the stock turbo up to the 550 HP range. These cams will not sacrifice any bottom end loss over stock cams; nothing but gains, and will promote faster spooling of the upgraded turbos. Gains of 20-50 WHP (depending on turbo) have been seen by simply bolting the S1 cams in.