i missed the swipe card bit in the tuning section...knowing that the 28 has teh card, im pretty sure to stay away from that model because im guessing the power is resticed and using the hrc card on the stock eletronics does almost nothing (that is what i have from understandng)
So the way i see it is that the MC 21 model is the best (most rewarding) to "Tune" ie. splice, disconnect black bullet plug, port and head polish, port bore, air box and exhaust derestiction....
Also i was thinking of miling the head or using a thinner gasket? would it be worth it (i have the mill and tooling - but is the gain anygood)
Oh and here is a 2 stroke performance tip - not sure if it applies for the NSR...
between the crankcase and the reed valves there may be a spacer, if so remove it and what it should do is that it reduces the crancase volume - this then makes bottom end power lack a TINY bit but increases the top end significantly, also some bikes (not sure for the NSR) if you preload the exhaust valve spring u get better performance in teh top too...