Thanks for that...makes sense. Would you ever want that power at 6 - 7 K as well though?
You can't have a peak in two places within the rev range. This is where R&D comes in, a few things can affect the way an engine is tuned. Take the Glees 650 motor, it's the Gladius engine, but the cams have been changed to give a less aggressive profile, so they open the valves for longer during a stroke but not as far as the Gladius cams, which open them for a shorter amount of time per stroke but by a greater amount. This, coupled with ECU differences to fuelling, can give the same engine two completely different characteristics, as demonstrated by the Glad and the Glee and, of course the SV650 and the Wee. Also, gas flow and intake profiles, length, and airbox design can all affect tuning.
You can't have it all though, low down grunt is always at the expense of top end power, a balance engineers have been playing with for generations.