Basicly without going overboard and reasonable gains on standard internals, front mount inter cooler, dump valve and full decat. All require remap.
Going a bit more you'll need to upgrade the turbo, forged engine parts, bigger injectors, fuel pump etc etc.
Body wise there's not a lot about for the Hatch unless you look to Japan and the states. Rear wings, defusers, body kits ect.
There are parts around the UK but it's mostly front lips, grills and that's about it.
Suspension, full range of stuff about, tien, eibach, whiteline, bc, kyb etc etc.