you know honda makes there rev limiter at the optimum point with there engines. if you go past that then your losing power.
hp is determined by how much torque there is at that rpm, so if your torque curve falls fast then maybe your losing power not gaining power. the only time ive seen a need to increase rev limiter is when you get a cam. its not alwasy the higher you rev, the more hp youll get.
decreasing stroke will make you lose torque