I agree with 'Impalawannabe' - HEAT! My RM sedan is black, and before I decided to sell all my car audio, I had 3 MTX 12's, each with a Kicker IX1302 pushing 400 watts RMS to each sub. On hot days, they would cut off on my several times during the day, even if I wasn't pushing them hard. However, it is very possible that you could have it wired too low. If the amp is not 1 or 2 ohm stable, and you wire it that way anyway, it totally overworks your amp(s). What setup do you have, and how is it run/wired?