I'm not sure what you mean Jeeks. I run a PC pipe with FMF shorty silencer on my 250. It is set-up very well. In fact, it runs so well that I am not even considering any mods. PC lenghthens powerband and may require needle adjustment from stock. The shorty silencer is a noticeable improvement to power also over stock.
If I was to do anything different, it would be a hydraulic clutch. Alot of control is in the clutch and if I were into any endurance type of racing, I would alter anything causing arm pump.