piston upgrade keeps killing my starter..

[Zzippp]

I just bought a 2001 hayabusa, the guy i bought it from put a piston kit in it, he told me that he has had to replace 3 starters already and i needed to do a 12v upgrade, add another battery and do a cross over on the batterys. I realy have no clue about this.. the bike starts with no problems cold after riding for a wile it takes a wile to start back up, This bike is a Canadian edition.. im not sure if there is much of a difference when it comes to the starters just adding all the info that i have :)
Can someone please tell me what i need to do about this problem or what a 12v upgrade is? also if i do nothing is my bigest problem going to be replacing another starter or something more major? Thanks :)