Ooo,

Thats hard, I think Aprilia RS250 is much easier to become race spec bike.

But can you tell me how to derestrict MC28 and increase HP to the maximum?
Also which parts thats not important to remove and decrease the weight.

I cannot replace MC28 engine with any other engine because I am entering a production road racing series.

On my mind now is Aprilia RS250 and Honda NSR250.