well 260 rwkw will deffo require a turbo upgrade, so doing things like manual bleed valves anf fancy dumps at the moment are kinda waste of cash, if you are going to do all this in a relatively small period of time, go for things like the intercooler, fuel pump, fuel reg, pod, and and 3" cat and cat back exhaust.
then once you've saved your pennys go for the injectors, AFM, ECU, turbo route, all these require the aftermarket ECU, so doing all at once will mean you only need to get it tuned once, all you can put a fancy dump on at this point.
as for clutch, tyres suspension etc...that can all wait but don't expect your clutch to last very long at all with 260 rwkw, mine died before i hit 200....might even die on the dyno, who knows but be prepared
tyres, well if u can avoid spinning them (have fun with 260 rwkw) they should be no different, but every time u loose traction then you are going to need new tyres
suspension, well again its optionaly but if u dont' wanna die its something u should consider