Induction kit, yeah do that
but the main draw back with the k&n and other filters like that is that they sit on top of the (hot) engine. You can feed cold air up to it, but its better to have the filter on some tubing and down nearer the front right handside of the bay. GSR do a kit that may fit the punto75.
HT leads, KV85 Magnecors will set you back £50 a set - maybe a bit overkill. Check out the cheaper bosch ones. Plugs, Champion Eon 2's are around £20 - can't go wrong with them
I cant help with exhaust, apart from suggest supersprint and powerflow. Remapping is a good idea also. I'm not too sure who does remaps for fiats, i know tuning concept do but its a lll pricey (£350).
Handling wise, lower it. Spax or apex springs. If you want to spend a bit more, you could fit new dampers/spring set like. Spax do some nice matched sets.
iirc brembo do some uprated discs for the punto, they're worth a look and stick a set of mintex brake pads on there too.
Hope that helps ya
Cinq Sporting - and yes, its
broom yellow!