I need an amp to power my JL 12W6v2. Im looking at the Kicker KX400.1 and the MTX Thunder 421D. I kno the JL 500/1 is supposed to be the best for it but they r so expensive and unless u all kno sumwher to find them cheaper I gotta get one of these. Okay the MTX puts out 420 watts @ 2 ohms which is close to optimum, but thats at 14.4 volts, it only puts out 300 watts @ 12.5 volts, not much but a little underpowered there. I dont kno what voltage the Kicker is rated at, thats sorta wat i need help w/ finding out. which would work best? Also, wat r the extension things on the Kicker amps for?