Welcome Yuri.
I love Italy. I returned there again this year (actually last year now) and spent July just having fun in 6 cities.
Does the car idle rough? Is that why you want to tune it up?
If so and if the car is original and it has been sitting a lot then
the injectors may need attention. If the injectors are original
they maybe sticking. Inspecting the spark plugs is a good place
to start too. Be aware, #8 plug is tricky. We've all developed our
own tricks to getting that one out
Do you feel comfortable working on the car yourself or will you
be taking it to a mechanic?
Again, welcome. You're in the right place for help on the ZR-1.