The 3g style apparently pump up too much in the topend making the valves float 10-20 thousandths.
FP recommends 1g style for high revving 5R/4R applications, etc. for this reason. Jake Montgomery switched back to the 1g's and gained quit a bit.
Actally straight off Fp's site.
"For very high RPM applications we recommend using the early DSM style HLA's (they have a smaller diameter plunger) and reducing oil pressure to the HLA oil galley by using the early JDM oil regulator or a restricted orifice in the oil distribution block. These two items reduce HLA pump up effects. "
Found here:
Forced Performance Turbochargers: DSM FP 5R Cam