Alt. Replacement

If your current alternator is keeping your battery charged, you don't need a bigger one. As others say, a bigger one could cause more problems than not. I also agree that if your lights are dim at idle, that indicates wiring and connector problems since everything should operate fine off the battery alone. The alternator's only job is to slowly recharge the battery. That said, the original round-back alternators have a weak output at idle, so if you spend a lot of time in stop & go traffic and drive short distances between starts, it may not keep your battery charged.