Improve the suspension without breaking the bank with:
Mild lowering springs eg tein
ARB polybush upgrade
OEM Droplinks
And a geometry alignment. Add good sticky tyres and brakes upgrade like braided lines, RBF, decent pads and disc and it will be worth 50bhp.
Adjustable ARBs are nice but to make the most of it you need adjustable droplinks to prevent binding and if you were going with these then you may as well use lower springs to lower CG or best still coilovers and this brings you into needing adjustable camber and toe arms!
Confused?! What I'm trying to say is make little adjustment at a time while keeping your tuning goals in sight. If not you will end up with a car that is worse than OEM because tbh OEM setup is not bad for normal use