You have remap so....
Full system exhaust from milltek, blueflame, scorpion or custom made
Intake from ITG, EVOMS, DBILAS, FORGE or the likes
Stage 2 map
That should be for the guts of 330/340bhp
If that is not enough for you then also consider a front mount intercooler (FMIC) and high pressure fuel pump (HPFP) and then stage2+ map - good for 360bhp or so
You will then have to consider a new clutch and if not already, an uprated dump valve to cope with the extra boost pressure.