the general rule of thumb is for every 100 watts of power an amp produces, it pulls 10 amps of current.
and it is a little less for Class D amps, b/c they are more efficient at producing power than Class A/B amps.
so if you have 3 60 amp fuses in the side of your amp, that means it can pull up to roughly 180 amps of current, which would be roughly 1800 watts RMS.
if it only lists the ones you gave me, then it isn't 2 ohm stable. and the only way you could hook it up to 4ohms to get 500wRMS would be if you had two Dual Voice Coil 4 ohm subs.
in which case each woofer would get 225wRMS. i personally would get a bigger amp, but as long as you don't turn up the bass boost on your amp and HU, and clip the amp(causing the speakers to get Direct Current instead of Alternate Current which in turn disables the voice coils from properly dissipating heat and melting them) and play them into distortion, you should be fine.
on the other hand, if they are single voice coil 4 ohm, or dual voice coil 2 ohm, then you can't hook them up to your amp at a 4ohm load, then you should consider getting a new, more powerful amp that puts out 700wRMS or a little more, b/c 100 watts to each speaker isn't going to cut it, and you will more than likely clip the amps and blow your subs.
