converter

I read that someone serial coupled two 12v batteries to make the starter motor turn faster. 24v worked good he said. I don't know how he then charged the two batteries with the 12v stator? My idea is to couple a 12v to 19v DC step up converter between the battery and starter motor. Then you...

Who has removed there catalytic converter from there bikes. If you have, do you need to have the bike remapped etc. Thanks