I am looking at getting a set of pullies for my 4.3, my only concern is that I have a 250 watt amp powering a 12 inch sub and I do not want to have problems with charging at anytime. What would be the best set to get for this, I am guessing that I would want the alt. pulley to stay the same size which would leave me with just replacing one pulley? Is that even worth it? Any help would be greatly appreciated.