ur budget can easily get u the best of subs... then y are u opting for a pioneer 309/310 combo???
the jbl p1222 is a beast of its own kind. its one of the best subs ever to be made by one of the leading brands in audio. it can easily take on the same power that the 2 pioneers will need all by itself. Same goes out for the Alpine type R sub.
if ur going for a SQL setup, the p1222 and Type R are ur best bets.
Followed by the SQ sub by Infinity and the SPL sub by CV. all of them are light years ahead of the entry level pioneer 309/310 subs.
There are outclass subs from Pioneer aswell including the 5000spl, 12prs, PRO but they come at a high cost too and are hard to find. however the 309/310 are their most basic line of subs.