2 12 Xplod's vs. 2 15 BMF's

I am in the process of redoing my system right now, and am starting to get a little bit worried about how much money I'm spending.  The last count was about $1300, including new wiring and an extra battery.  So my question is, I bought 2 12" Xplods and an 800-watt Sony amp a couple years ago for about $450.  The subs are in a sealed box.  I am now looking to replace all that, and just bought one Crossfire BMF 15" today for $250.  I am going to put two BMF's in a ported box, with a VR1000D amp and an extra battery.  All the previous wiring has to be redone to go from 8 gauge to 4 gauge.  All that will cost about $1300.  I don't know too much about audio stuff, but I know that Sony Xplod's are crappy.  I just want to know if you all think I am justified in spending all that money to replace the system that I only paid $450 for.  Basically the question is, is the cost worth the benefit?  or will the crossfire system only do a little bit better??  Just want your opinions please, before I spend all that money.  Thanks.

the crossfire stuff will kill the sony stuff   thats like comparing a pitbull to a pug in a dog fight what kind of head unit /cd player are you running and you can get the 4 gauge amp kit for about $30 at walmart of all places one other ? for your mids and highs what r u running1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700

i'm running the factory head unit, a six-disc in dash cd changer.  i can't replace it because if i do then my factory DVD system will no longer work properly.  so i'm stuck with the factory head unit.  My mids and highs are all factory, most likely going to replace those later on in the summer

i dont think thats a good idea your factory speakers are matched tyo the power of your factory head unit just add some cuspid tweeters  you can add those thay have a tiny crossover inside that dosnt change the load your headunit is running you can get those from my buddys shop for like $15 and as far as the extra battery kinetik batterys are the way to go1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700

what kindof ride do you have1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700

ive got a 2003 explorer

vented

thats cool instead of puting an extra battery in u should just replace your main battery with one of the kinetikbatterys the hc1800 will do the trick check out www.kinetikaudio.com  there expensive but worth ever penny with a stock alternater you can run 2 kx 1200.1s with no problems 1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700

just replace the regular battery with one of those?  which one would you recommend?  i don't really want to put in a second battery because i'd have to find the room for it, and i dont want to do that