if I'm wrong on this but from what I've read the loss for FWD is from 8-15% While RWD is anything from 15-25% so using the outside limit on either end produces a 15% loss on FWD and 25% on RWD. Making FWD car that produces ~550WHP actually ~633FWHP While a ~550HP RWD car is actually ~688FWHP.
Devils Advocate Flame suit on. ~550 dyno on a FWD Honda could be ~594FWHP ~550 dyno on a RWD Z32 could be ~688 FWHP producing close to 100 HP more at the crank. So what I'm trying to get across is that the Z32 is actually producing more power on pump gas then the FWD Honda, The Z with less boost and smaller turbos. So a Z32 that dynos at ~450 is producing the same crank power as a FWD at ~550.