PU a RE sub from someone here or new. If you want it to be loud then go with them. I had 2 10" JLw3v2 powered by a JL500/1, switched to a RE SExxx with the same amp. HUGE difference, RE sounded cleaner, louder and bass hit deeper. With 700, I'd say drop 200 for a RE sub, 200-250 on an amp, someone here will have someting powerful enough, build your own box, decent set of comps, alpine 4 channel for you mids and highs. You could also spend what you have now and save more money later for mids and highs, then put it all in at once.