300bhp i reckon would be achievable with, Hybrid k04 turbo. Panel Filter with air feed, frount mount cooler, the usual bits such as tip, hoses, 007p, turbo back exhaust, downpipe, cat + at back and a good remap would surely see you on the way to 300 if not just a bit short.
Most big turbo kits run over 300, more around 350 up to 400. So the internals would have to be uprated to take this power, engine would need a rebuilt with the uprated internals, conrods, bolts, piston rings, bearings. injectors, stage 3 remap, manifold, gaskets a few things form top of my head but sure theres a few more. looking around £ 3500-4000 for a 400bhp. then you will probably destory gearboxes and many other things.