F150 Super Crew System

[tweezy79]

I have a 2001 Ford F-150 Super Crew truck. I recently had a box made that holds two 12's to go under the back seats. It is a sealed box with 1.2 cubic feet of air space with a mounting depth of 6.5 inches. I don't have a lot of air space and am having a issue with deciding what subs to get. I am into rap and am looking to get the best bang out of the box without destroying the subs. I am currently looking at the FI SSD's becuase they have the perfect mounting depth and can be put into a sealed box. My issue is the amount of air space they need. A single 12 inch SSD can be put into a sealed box with .8 to 1.6 cubic feet of air space, but I want two 12 inch SSD's. I am afraid that I will bust em or they'll blow from not having anough air space. What should I do???????????

Here is what I have as far as equipment goes.

Alpine IVA-D106

Audio Control 3.1 EQ

(2) Alpine SPX 6 1/2 component speakers

Alpine MRP-F600 150X4 RMS@2ohms

Alpine MRP-M2000 2000X1 RMS@2ohms

Any HELP would be greatly appreciated. I guess my question is, will the subs sound like crap or blow from not having enough air space? Or should I just go with one SSD 12?