i gota ask...if you want highway speeds....why would you change to a lower drive sprocket?? and comparing the gearing of the XT to the other 2 bikes can't be justified as they all have different size rear wheels
So the engine spins faster.
It depends on the shape of the torque curve, but generally, higher rpm = more power. Top speed is when power = drag, and that may or may not occur at max rpm. So if you can change the gearing such that the engine is making more power at a given road speed, it's possible it'll go faster assuming it's got the head room to spin faster.
This shall pass, be still and know.
2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.