my mods now are the following on a trail bike:
dune play port, 65mm cylinders with pro lite wisecos, 28mm carbs, pro flow filter and adapter no lid, milled stock head (or cool head 19cc) depends on which i run, stock radiator, billit impellar, +5 timing,vf2 reeds, billit clutch basket, stright cut gears, welded crank, fast racing clutch, 15/40 gearing. i mean 180 on tight trails is fine with me.