if u want to keep the amp u will have to change ur sub to either a Single 4ohm or double 2ohm model.
ur amp say's it gives out 600rms@4ohms bridged but BOSS do over rate their amps so im guessing the amp should be giving around 350~400rms, though one has to check this but the assumption can be made.
so u will have to use ur current sub at an 8ohm load and that would not be a good idea.
So either get a Pioneer 309S4 or a Pioneer 309D2, connect ur sub at bridged and u should be good to go