I can recomend you Honda - Sundiro kit buyed from
www.revolution70.com My auto mechanic install it when Agility has 2000 km...now is 26 000 KM on counter, and still running ...
Its 72 ccm kit ( Known as 80 ) 47 mm bore diameter, original head. Kit is only real improve of Agility performance, all other are children games ( of course you should derestrict, cut CDI, and put little lighter rollers egz 6,2 gr ) My Agility also has KN intake filter and catalisator out exhaust,,,,,speed is 75, but the kit doesnt give you speed , just agility ( power )
NCY kit is in my opinion best solution, Polini is just a name, but even a 25 $ ebay kits if installed properly are good solution