I have had two friends both run 4 door blazers, both did subs up port back, one did an aq 3500.1 on 3 sa-15's but the box didn't have enough port area, did about a 148. The other actually used 2 of those same sa-15's and an orion 2500 with a similar setup and got a 152.5 out of it.
Since your subs are dual 2ohm i would get 1 big 1ohm stable amp that you can burp at .25 and run at 1ohm daily. - if you do competitions. Are you trying to build a wall? bandpass may be hard to fit back there in a "no wall" application.