are these things any good and what kind of a difference do they make. alot or hardly any......have a chance to buy one but never had one before

 

i have one and they do work, there are suppose to make it start better and worm up faster and stuff and mine starts first kick almost every time, but some times 3rd kick if im having a bad day[img]i/expressions/face-icon-small-confused.gif[/img]. but yea man you shounld get one.