300 watts peak or RMS?
Always look at the RMS rating, never mind the peaks. They mean nothing.
If it's RMS, then you'll need an amp that pushes 600RMS depending on what you wire it to.
If you wire it to 1ohm, you'll need 600 @ 1ohm.
2ohm would be 600 @ 2ohm, etc.
The wiring depends on the ohms and voice coils of your subs.
If they're dual 2ohms, you'll probably wire them to 2ohms.
If they're dual 4ohms, you'll probably wire them to 1 or 4ohms.
Here's a wiring diagram to help you decide.
www.the12volt.com/caraudio/woofer_configurations.asp