The GSC Power-Division Billet S1 cams for the Mitsu Evolution X are designed for those with the stock turbo up to the 550hp 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 20-50whp (depending on Turbo) have been seen by simply bolting the S1 cams in.