I guess I worded that bad.... With the premium sound that came in my car it came with an amp and I was told it might not be able to power 4ohm speakers so I was wondering how I could tell.
Your best bet is to look at the speakers, not the amp. If the stock speakers are 4 ohm, then the amp will work on a 4 ohm load. If they're 6 or 8 ohm, it probably will not like a 4 ohm speaker.