Depends on the budget. You can go all out and completely rebuild it with forged pistons and rods and such. But that will cost a few k.
Or you can do it cheaper and go with 1.0 pistons (and 1.0 flywheel). The pistons raise the compression ratio.
Then drop in a set of cams and a good exhaust manifold (and intake manifold or itbs if budget allows it. With itbs you need bigger injectors like the ga16de ones). Add a Ga15de throttlebody and ideally you want it mapped. Will make quite a quick small car. Add the 1.0 gearbox if you like the acceleration of it (0-60 somewere around 6 secs)
