New subs and what to get next!!!

ford01explorer

I jusst purchased the db212 dual 12" enclosure and have it running on a kenwood kac9152d pushin baout 900 watts rms. It sounds pretty damn good but you can always have better. If anyone else has these subs i would love to hear their views and their setup. Are these subs considered good or what are yalls thoughts. im semi new to car audio but not what id call a newb, hah. also, i am looking to upgrade to new better subs once i save my money all over again. what would be a nice step up mostly in sq, open to mostly anything such as the sr's, w6v2, or others but i love polk. great stuff. THanks