I'd go with a Mugen intake or the complete ARC induction box. I use a Comptech intake + icebox which is also a very good setup.
I'd leave the intake manifold/plenum alone and just go with a 70mm throttle body.
As for header, I'd stick with a JDM 4-1 (unless UK-spec R's already have it) or Toda for maximum gains.
Stick with a Skunk2 or Omni testpipe because they have a bung for the secondary O2 sensor (no annoying CEL).
If you don't mind loudness I actually prefer the J's Racing circuit titanium exhaust. It's pretty, lightweight and you get very good gains off that too.