264's to make the car still feel fairly stock standard on tick over or 272's to make it feel like a V8 Range Rover running on 3 cylinder's on tick over!!! This is my own personnel view on it BTW
Mine has 272 and ticks over fine with no lumpiness. previously had 264's on a stage 1 tuned car and found that boost came in 300 rpm lower down the rev range than standard which equals an increase in torque:awesome:
264, 272, 280 are all for reference. You don't always get exactly what your buying. You'd need to specify the make of cam to be more accurate. You can find the same '272 profile' but different makes will give different characteristics. Generally tho you can fit any make 264 on std springs/retainers. But fitting 272 or higher you need to fit uprated springs/retainers. Kelfords Hks Gsc Brian Crower