Welcome to the club

You won't get much more power from the 1.5 engine without some serious work, which you'd have to question the financial reasoning behind!
You COULD buy an existing turbo kit, make up your own manifold flange, modify the piping (though it's probably more work than just building your own log style manifold) and yes, of course it will work - turbocharging is turbocharging at the end of the day, but don't expect it to last long... the engine internals of the Z5 aren't particularly strong, the clutch is tiny and will start to slip, and say goodbye to the teeth on 3rd gear pretty quickly!

The F series gearbox which you will have fitted, sources say they're good for up to around 200bhp if you're careful, though some have gone higher with them, others have exploded at lower power levels. The standard clutch might be alright up to about 150bhp if you're careful and it's in good shape. The internals will take a beating, but won't last long - if you're running around the 150bhp mark I reckon you'd need a new engine in less than 10,000 more km!
There's also the issue with running it - the standard ECU works off a MAF sensor, which won't be particularly welcoming of a turbocharger (ask me how I know!), so you'd need to either run really low boost and larger injectors (not worth the hassle), or run a standalone ECU (very expensive, ask me how I know!!)
With all the intake work, exhaust work, oil plumbing, coolant plumbing (depending on turbo), electrical work (you'd have to wire up a bespoke ECU yourself), you might net yourself 150bhp, for another 10,000km before having to replace/rebuild the engine, all to the tune of around £2500 if you're doing it yourself, more if you're getting a garage to do the work. Worth it?
