Currently I have a Pioneer DEH-P6800MP with 4 Polk db650s. I am looking to add an amp, probably a mono, and 2 subwoofers. Im thinking 10" subs but am wondering if maybe 12" would be better since its a big car. I was looking at some Rockford Fosgate P2D410 Punch 10" subs, but Im open to anythying else that may be better. Also, what size amp would I need to power 2 ~500w (250w rms) subs.