I use to work for a Crossfire dealer and installed the amps for 3 years and had nothing but great experiences with them. I've toyed with the 1000D's and those amps are amazing i cant imagine what the 4000 puts out (more than most women) Crossfire rates all of there amps at 12v so your not getting cheated out of any power. i would recomend
I have been running two crossfire amps for about 4 years now, one of which is the vr1000D and I have nothing but phenomenal things to say. I run the vr1000D at 1 ohm and have been for that many years every single day and I can't say enough about the loudness of my subs and the reliability of those amps. You won't be disappointed. I won't run anything else.
Careful on the vr4000. Reason why I ended up getting 5th at finals a few years back is because I ahd to run half the power as everyone else because my vr4000 went up in smoke. Very gentle amp but lots of power if you get them running right