Sub box for Alpine Type R

[minesbroken]

Honestly, I don't know. The subs are Insignia (Best Buy brand) subs and they sound pretty good. They're in a bandpass box and i got them on craigslist for $50 all together. Good deal at the time.

More efficient it gets? If I match it with a new amp with sub's wattage RMS shouldn't it be fine? I appreciate your input, help me out.

The type of box you build greatly effects the power handling of your sub woofer's
when they stamp an RMS rating on it it's usually in optimum conditions.
If a sub woofer handles 500 watts RMS that is going to be in a sealed enclosure built to spec for the sub. when you make the box bigger the sub woofer moves more freely (more efficiently) and cant handle as much power but also doesn't need as much power to do the same job.
Ported/vented enclosures are the most efficient designs, and therefor your sub woofer will have the lowest power handling in a ported enclosure.
Kicker for instance rates my woofers at
200 watts RMS compact sealed SPL enclosure
140 watts RMS maximum sealed SQ enclosure
75 watts RMS in a vented/ported enclosure

The more efficient your enclosure is the smaller amp you can get away with and still have good response.
I run 4 Kicker CVR's
8 Inch CVR'S
with just 2 of them on a cheap alpine v power 400 watt RMS amp I hit 141 DB.
It is louder with 4 of them but I haven't had a chance to put it on a meter yet.
I case you were wondering I hit the same DB with two JL 12w3's in a sealed box with a 500/1 JL amp as I did with my two 8 inch kicker cvr's but the two 8 inch subs only cost me 50 bucks each.
Amplifier RMS varies also.
Almost all amplifiers are given they're RMS rating at 14.4 - 14.8 volts
Most cars run a voltage of 12.9 to 13.8 volts, so in most cases you amplifier isnt running to its potential anyway.
If your amp makes 1200 watts at 14.4 volts and your car is only giving the amp 12.8 volts your amp may only be giving your subs 1100 or 1000 watts.
Get a multimeter and test voltage at your amplifier while its playing really loud and you will see the voltage drop as low as 11 sometimes.
at 11 volts it may be putting out 900 watts and probably getting hot trying.
there's a lot of factors involved.
You want your amp to be at proper voltage when its playing very loud and your car is idling.
if it isn't then your not making enough voltage to run your system.
consider an alternator upgrade and another battery.
with my 4 8's I run a tiny amp, get huge deep bass and my lights don't even dim with my stock alternator.
my voltage at the amp never drops below 12.5 volts even with the car idling.