[Riveted1]

Yep those guys know their stuff. ^

Ok, this is what I would do: (Sorry it's so long)

I would buy a 6.5" component set. Find a store (preferably a REAL car audio shop) and listen to several pairs and pick out the ones you like the best. Note they will sound different in your blazer, but that's the best way to pick out some you like.

Build some kick panels like was suggested above and mount the component set in there. You can find plenty of info on the web about proper aiming of the speakers to get optimum sound. Run these off of the front 2 channels of your Infinity amp. You can also use the high pass filter on your amp to cut out some of the lows from your component set so they don't distort at high volume (or use the one on your head unit if it has one.)

Now find a spot for the 6x9's and run them in some sort of enclosure. Run them off of the rear channels of your Infinity amp. I would use the high pass on these too.

Now for the subs, I don't know what model those are. But I would suggest (also mentioned above) that you buy an amp just for the subs. Usually take the RMS power handling of the subwoofer or both subs together (if using a mono amp) and find an amp that is just a bit more powerful than that (RMS).

I would build a custom box or boxes for the subs. Something like firing in from the side panels or down behind the rear seat. You can build a big portion of the boxes over the wheel wells to use up that almost worthless space. If you don't wanna get that crazy, the box you have would probably work.

Amps can either be mounted under your seats or showcased as a part of the sub boxes, center console, etc. Depends on how flashy u wanna get.

Make sure you run hefty power wire and ground wires, and always use a master fuse or circuit breaker near the battery.

Also be aware that a topless vehicle will need a lot more power in the bass department to be audible when driving down the road.