Oooh a hairdressers car eh!
Well I can be a bit of a tart so I guess I fit the car well then!
Anyway, back to the bloke stuff! The TU5J4 engine is regarded by quite a few people as one of the last 'highly tuneable' engines produced. More and more modern cars are increasingly difficult and expensive to tune, often with few real gains.
As suggested cams and t/b's is a great route to go down.. But quite expensive and with more gains than it sounds like you really want. Realisitically you are looking at 160BHP easy with a set of catcams 708's or similar cams alongside a decent remap or mapped stand alone management. You could probably get 140 BHP with decent breathing mods. You are looking at:
Good quality enclosed induction (Green
MC or the like)
Full stainless exhaust system (de-cat) inclusing a 4-branch stainless manifold.
You could look at other modifications such as lightened and balanced flywheel, head work or work on the throttle as the inlet is quite restrictive. But what you have above is a good base for future modifications without breaking the bank in one go. Personally I would want to pour more money into suspension and breaks anyway.