If you've ever driven a new 182 Cup you would realise how good these cars are. I still regret selling mine.
A new exhaust is worthwhile if the old one is rusty or falling apart, but be careful you don't get a droner. Many people complained of droning exhausts with the 182.
Tune for drivability? Forget it, the car is amazingly flexible with gobs of torque at low revs, you have 80% of the torque available from 2000 rpm.
Shocks, at least replace with OEM shocks and new bushes. Also look at your steering arm bushes, engine mounts etc as all wear out and new mounts make the car feel nice and tight.
A 4 km commute? Find a longer way home. Your engine is barely warm in 4 km
cheers, r