Ok, so I've been trying to do a little bit of studying over different kinds of woofer enclosures and options that would work for an '88 firebird. As everyone may know, I have 2 15's and a 12" (stats below), and am "trying" to go at a bit of a different approach. This is what I'm thinking:

To my understanding, a sealed box with extra cf tends to make lower, deeper lows, and sealed boxes with less cf tend to be more aimed at faster, quicker punches. They both have their strengths and weaknesses, though a larger box is desired typically. My woofers are:

2x 15" Hifonics Brutus BX15D2:
*700 watt RMS
*1400 watt peak
*DVC and 2 Ohm ressistance
*27.57 Hz Fs
*SPL: 97.84dB @ 2.83v

1x 12' Pioneer Premier (yet I'm not quite sure exactly WHAT model it is, and it's SNUG in a box right now so I can't look around the basket for any model #s or anything. The only info I have is this picture:

I'm not sure how old it is at all, just strictly that picture is the only hint.

So I was THINKING of making boxes for the 15's that have around the max recommended cf and keep them in the back of hatch. This will make some damn strong lows. Then I was thinking, since 15's aren't as quick or responsive as 12's are, of keeping the 12" in a smaller than recommended enclosure, so it'd have an easier time w/ quick punches. I figure it'd make sort of a "checks and balances" system that would cover all of the lows. If it makes things change any more, I'm planning channeling the maximum recommended power to each woofer as well, so they'll be hitting to their full potential.

As mentioned, I'm still really new with this all, so I wanted to get everyone's opinions on if this is a disaster waiting to happen, it works, or if no one's ever really bothered trying. I was also considering making one or the other a ported enclosure rather than a sealed one, if that would make things any better. Thanks

 

It does not really make sense to have the the 15's for one application and the 12 for another. I wouldn't bother mixing sizes. You need to decide what you want. Do you want to hit hard or hit low. If you want low stay with the 15's if you want hard than go with 10's possibly three of them or 12's in a sealed box. Follow the recommended cf for the sub for each enclosure. Do not go with more cf than recommended or the woofer will not be tuned properly. You could also go with one speaker and put it in a band pass box. Also the 12" Pioneer in the pic is a good sub. Looks to be a few years old but the Premier line is Pioneers top of the line.