If I was going to do anything of this nature, I think I would most probably opt for;
VWR panel airfilter,
Stage one VWR re-map, (claimed 260bhp & torque optimised),
VWR exhaust rear section,
VWR limited slip differential - fast road,
Uprated brake pads, again from VWR.

I’ve never played with any of my previous cars and haven’t swapped anything on this one, yet.....