If you do it all just go stage 2

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Stage one will be fine with all stage 2 mods minus the FPR. So that would be, Intercooler/TIP/DV/turbo back exhaust etc etc... Stage two just pushes the car harder because it can handle it fine with the modifications.
The 1.8t can handle ALOT of power for a 1.8 block, to get over the 250 mark and hit the 300 mark your going to need a turbo upgrade along with a few other things to suit.
I would say its not that expensive to see 240hp out of a 1.8t but anything more than that will require some $$ as even upgrading to K04 turbo etc is going to cost quite a bit on injectors/maf etc where as, do all the necessary mods and have plenty of cool air flowing around the turbo you can achieve 240 IMHO on a k03s.
** if your just going for a stage one... probably save your money on half the mods as their generic maps and wont be taylored to loads of modifications and TBH on a stage one you could generally see more turbo lag running a FMIC.
** clutch wise, get a spec one or g60/vr6 conversion, cheap to do and will handle 300lbs of torque... standard clutches are a bit weak.