I have used a NGK Race Coil and lead on all the minibikes i have had they are really good can get them on ebay just type in NGK Race Coil and it will come up under $60 free post. These make a big differance over a standard one the bike starts easier, smoother idle just better over the whole rev range.
/\ +1 I'm with Rodney, I've tried a few coils and the NGK lead is the best I've had buy far. I've got my NGK lead teamed up with a takegawa super coil and a iridium NGK plug and the bike starts first kick every time and revs clean, heaps better than stock.
These bars should be 22mm in diameter, if your bars are bigger than that(fat bars) then you will need different risers, post up some pics of your current risers where the bars attach to the clamps.