soundsplinter rl-p > alpine type R's..........overall just a higher end sub......there's a good chance that for $300 you'd be way better off with 1 high end sub than 2 medium grade subs. SQ wise and SPL wise......
from my experiences.....i've had 3 infinity perfect 10.1's, 3 JL 12w3v2's, and heard numorous systems consisting of medium level entry level subs, many ported and many sealed from 2 subs to 6 subs, and my 1 XXX 15 ported sounds as clean and WWWAAAYYYYYY louder than most everything ihave heard (exept SPL vehicles with stupid amounts of bass)..... i spent a hefty penny on that sub but MAN it's worth it. with ur budget IMO get a single sound splinter rl-p and run ur amp to it mono (if u can)....800 watts on an rl-P is plenty to get it wangin.....http://www.soundsplinters.com