Polk Audio MM1240's in Sealed or Ported?

Hi, I want to know if the polk audio mm1240's sound better in either enclosure?the amp which I was thinking...the Alpine MRP M1000,Aq1200d,or something under $300.I have the db 651's,db 691's and are hooking them up to an eclispe ea4200.Can I bridge the back speakers to get the full rms out of them?Or is 140 watts too much?Thanks