well from experience, i have two 3004 12"ers in a slot port box (built by myself) running off the kicker kx 1200 in a toyota corolla and hit 139.1 db last weekend at a iasca competion at mobilink audio in marianna, fl. the subs can handle much more power tho, by a long shot..
what size r series subs are they? The bigger they are, the more power they can handle. I'm pushing two 15's with roughly 450 watts rms into each and they dont bottom out at all, not sure what size the box is, i got it for free, so who cares?