The YBR is not a sports bike so you´re limited in what you can do to increase top speed... I am sure what you have done already has helped with torque and acceleration. Also, run your bike on Super Unleaded (98+ RON), it makes a good difference on these bikes and also helps the engine stay clean and last longer. Have you changed the spark plug for a decent NGK ? Aside from this, have a look at the aftermarket fairing that is available for these bikes (from Spain I think), it makes the YBR look even better than a CBR ! Really sporty and will also give you at least another 3-4mph on your top end, if you keep your head lower.