The Billet GSC Power-Division S1 cams for the Mitsu Evolution 4-8 are designed for those with the stock turbo up to the GT30/50Trim. 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 30-55whp (depending on Turbo) have been seen by simply bolting the S1 cams in. Designed for a rev range of 3000-8000rpms, these cams work well on the stock valve springs. 300-450whp camshaft. Idle is slightly rougher than stock. Made 100% In The USA