GSC Power-Division billet S1 cams for the Hyundai G4KF Theta 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.
Designed for a rev range of 3000-7500 RPMs
The S1 cams work on the stock valve springs, but its suggested to upgrade