you can really feel the stock option sub its right under the seat

 

The enclosure is just as important as the subs... you cal *feel* 2 8s or a long excursion 12 in a well built and tuned enclosure. So yeah you'll feel 2 15 JLs.

 

FYI, I've got a couple JL 10's in JL enclosure and it hits pretty darn good. Hits more than good enough for whoever's inside, and still is "quiet" on the outside.

 

Dude....two JL 15's, specificly any JL's above the W3V2's is going to be overkill....Check out the JL 8W3 V2....great little sub, doesnt draw a stupid amount of power, and with a well build and tuned box puts out beautifully clear sound with enough bass if you so choose to rattle your teeth loose.

 

i run one 8w2 and it hits just fine in my STi.
if you like more, 2 8" would be plenty in a will tuned system.
BIGGER does != better or more.

 

i have one 12" Alpine Type R sub in a QLogic Box, w/ a 325 watt MTX amp. it kicks in my RSX, so im sure it would be good in the Rex. im gonna try and see if i can just get the wiring extended from where the stock sub is to the trunk. instead of taking out the dash to hook up w/ the HU.

 

Is there a way to get more power to that sub by connecting an amp to it somehow without changing the deck? I call the sub the "Ladies Option" gives some vibration up in the joint!

 

your Deck, or Head Unit, and your Sub have nothing really to do with eachother when it comes to "power." correct me if im wrong guys. besides like tuning the EQ the HU and Sub are seperate. you need an Amp to power the sub, and the amp is connected to the battery somehow.

Or do you mean that amp/sub that comes w/ the WRX and is under the passenger seat? that cant be any good, go aftermarket.

The Head Unit powers the speakers inside the car. So you want a Head Unit that is strong enough to power the speakers so that its not over powered by the thump of the sub (like in my car since i have a 50watt stock HU). this way it will sound like surround sound instead of an uneven BOOOM music BOOOM.