I am upgrading my sound system in my car this summer. I currently have one rockford fosgate punch level 3 10inch sub. I have been looking at many subwoofers and i am wondering, is a subwoofer that has 2 ohms vioce coils better than one with 4 ohm voice coils? the Rockford fosgate subs all have the option of the 2 ohm model or 4 ohm model, but they both cost the same, why is this? Is one better than the other? Ive knowticed most amps put out more power @ 2ohms than 4 ohms. does lower impedance lower sound quality? One other thing, i am looking at the Audiobahn immortal series, the 10 inch ones are only ~$200 online, and they are 1500watts rms, have quad 2ohm voice coils, and amazing specs, but they seem to good to be true for this price? Are audiobahns really crappy subs? How can they be so cheap compared to the other subs with the same specs, also is there a difference between these audiobahn subs with quad voice coils and dual voice coils? i know dual is way better than one, so im assuing quad owns dual?