If i hadn’t gone turbo, i would of looked at G60. I did look into it a few years ago but with the G60 charger failing more than a g40 charger, i thought id leave it. However, i was at the point of looking for more power when already at 170bhp. If i had a standard G40, i would be very tempted just to bolt a G60 charger on and see what it would be like.
From a discussion on this similar subject, i think the G60 flowed almost 1.5 times more air than a G40 and the G45 charger was still less flow than a G60 but obviously more than the G40. But that was figures on a standard G40, there was never any figures on a ported G40 or even a ported G40 with 65mm pulley.