just got back from a dyno run and a bit of a ride (you got to in this weather!). i spoke to the bloke and he said it has a flat spot at about 8k-10.5k rpm, which feels about right. the bike has a k&n filter, engine work (ported, polished, skimmed head and gas flowed), micron downpipes and a Fuel stubby oval race can.
its not brilliant but i dont plan on doing much to it as i want to sell it once ive got my zx7r up and sorted. maybe run some redex through it and see if the carbs clear it a bit.
anything is possible with enough time and money. and an open mind...