what hasnt been mentioned yet is that a huge part of the "speed" difference on the straights begins in the corners.
I have been in the same race with the likes of kevin curtain on an r1 in australian FX series and seen him blow by s1000rr's.. The FX rules dont allow any engine tuning other than full system and pc3 and his bike is regularly dyno checked after each race day (since he wins a LOT). each time the power figures are 155-158 RWBHP while the beemers he is racing put out the healthy 180-185
the key to his straight line speed is getting a much better exit out of corners due to the suspension set up/throttle control/skills and massive balls of steel! lol
outright bhp always helps but it does come down to a full package. my 07r1 has no problem keeping up with the new zx10s and gixxers that put out good 15bhp more provided i get on the gas well.
i only just had head work done to my r1 and have gained about 10bhp but the biggest improvement is in how much faster the bike revs (so even with similar power it develops it over a shorter period of time) but also a really good dyno tuno. with the new tune the biggest difference isnt the top end but, how early and hard i can twist the throttle out of the corners. the increased pick up off 0 throttle is staggering compared to stock.
also, peak numbers are very deceptive. you only use the peak power for an instant. what counts is the total area under the power curve and how early in the mid range you have good power. that will determine how well you get off the corner. no one is at peak power at the corner apex.
one last bit.. AMA rules are very similar to ASBK (australian superbikes) from what i can see so those bikes most likely see somewhere around the mid 180-190 bhp at the wheel but keep in mind that those engines are torn down and inspected after each race for a factory team and rebuilt after each season if not sooner. you could not sustain that power in a road bike and keep reliability. i have seen a race piston come out of a 07 r1 that produced 200+ bhp at the wheel, and after half a season of racing the piston pretty much just crumbled away from the gudgeon pin. they just dont last