Thats your answer... 121bhp on the 1108cc
121bhp - 8800rpm
124Nm - 7000rpm
It has 4x 40mm Trottelbodys.
Made by Leone Motor Sport
http://www.leonemotorsport.it/P_228_CINQUECENTO.html
About the 1368cc 8V engine with more than 150bhp, I found this artikel.
It is not the one I ment, but you can read some.
http://www.italiaspeed.com/2007/motor_shows/autosport_international/fiat/panda_evoluzione/1501.html
This i with 1 TB, with 4TBs the power is 162bhp.
Well, both are full race engines. The Leone one has some titanium pieces and runs a CR of 12 to 1! Technical Italian is difficult, by I think it has lightened rods (possibly crank), much of the valve train in titanium, big valves and a steel crank. Note that a (close ratio?) 6 speed box is available (and, presumably, necessary).
How much money do you have, Steffan?
Here some pics of the 1.4 16v car which finished 3rd in the national endurance racing championship.
I'd lay odds that the Polski one cost a lot less to develop.