ok if you wanna compete in db drag then street stock .you need 2 12 inch steel stamped basket woofers ,like the dd 1512's,also a 2000 watt rms amp.just to start.build your box ,tune it around 36 htz. should play the low and higher bass notes.or do a aero port 6 inch subs front and port front .biggest issue will be getting the box right ,and sealing the trunk .2 15's might be a little too much as i dont think you'll have enough room to at the trunk entry for the woofer and the port area.also port on the drivers side .with the 15's you'll need at least 6 cubic foot plus port are .i know the trunk is big but thats frt to back , not side to side.thats why i'm thinking 2 12's instead.or even 1 18.