do you understand what the sub will take? why don't you get 2 hdc3 18's on 2 aq2200's put your buddy to shame and sound better doing it... thats ASSUMING you've got the 250+ amp alt and 3-4 big boy dry cell batterys thats going to take, dekas, spv's, hc2400s, oddesey, whatever the choice may be. you do realize even with 2 btls, you do realize between the batts, the 1/0 wiring your going to need everywhere, 2 18s, 2 amps to push it (or 1 big one, a 40.1 might run 2) is it worth 3,000$ to "top" your friend?