Get a custom rolling rod (dyno) tune.
-It's safer
-will get you more that the 135HP of the Abarth
-You will see what you pay for (dyno before, while tuning, after)
Oh, an tune i with the kind of petrol you will be using daily (95/98/etc octane).
If you tune it with the best out there you should not use below that in the future because it will probably ping.