Tomei SR20DET Poncam and Procam Camshafts are one of the toughest and best cams made in terms of HP output and engine response. The cams were maximized so that adjustable cam sprockets may not be required. We only carry Poncam as a 256 IN / 256 EX combo. Anything other duration is considered as the Procams, which requires valve spring changes for higher lifts. If you need to mix and match ProCam durations for either Intake and Exhaust, please call in. For example, you may go with ProCam 260 for Intake and ProCam 270 for Exhaust.