I think the restriction is done via inserts in the carbs. When I had my bike Ivanised by Mike I recall him saying that he had just worked on a bike and discovered that it was a restricted one, and that he had removed the inserts from the carbs, so the guy who didn't realise it was restricted ended up gaining ~34 BHP from Mikes work and was more than chuffed.
This post from the old forum may help - http://fazer1000.yuku.com/topic/768/Sort...Zzz8U3bJaQ
This post from the old forum may help - http://fazer1000.yuku.com/topic/768/Sort...Zzz8U3bJaQ