I recently bought 2 12'* in a box and a 460 watt amp from BestBuy. They hit but not hard enough, is it possible to run 2 amps off the stock alternator and battery? And also what about some of those high watt amps off ebay that are really cheap. Do they actually work good or are they shitty?

Go ahead and buy an exact match of your existing amp your alt can handle it.

Yup, stock alternator should handle it. But you may get dimming on the real hard hits.

I would stay away from the amps on Ebay. Most of them are generic amps. Others are refurbs or in the "grey" area. Byt ehy way what subs & amp did you buy. I would return the amp that you have and get a bigger amp. Youll have to rerun your power cable if you have an * gauge to a 4 gauge.

No name AMps always have some big Watt rating PEAK.. but what you need to look for is RMS and distortion level.

If you can come across like a car auido magazine 2004 product line up those would help out alot. It pretty much carries all the newer stuff in detail. But like Drifter said definently check out RMS power & THD level. Also make sure you are reading the right power stats wethe its for 12v or 14v.