Help me pick a amp for my car sub woofers?

If you're talking one type R ( you did say 'sub woofers' plural) that is a good match, as it will push 500 watts RMS power to the sub at a 2ohm impedance. If you're talking two subs, it wont be nearly enough, and an Alpine MRP-M1000 would be much better to give them the 500 watts each that they can handle. Another comparable amp to the 8105D is an Alpine MRP-M500, which will give you the same power in a smaller footprint.