Ian , I know absolutely nothing about the technicalities of measuring power output .
Looking at various bike magazines I have lying around , they all quote dyno measured rear wheel power in bhp ( and torque in lb.ft )
This may be incorrect but it seems to be how things are disussed/compared in the bike world .
As S B Mate suggests , I guess the main thing is to compare like with like .
And S B Mate , S&S engines produce a lot more power in other applications so it ought to be relatively easy to improve it .
As for increasing mpg by 10% I suspect I could achieve this with my right foot , but it wouldn't be as much fun !
Also baring in mind the mileage most M3Ws are doing the savings wouldn't amount to much ....
Btw , I don't feel my car lacks power , but it's always nice to have a bit more
