This weekend was the first time I finally got to test the 4k2d on good electrical from another person car and we got 5000w 12v running it a little less then 1ohms rising to 3-4ohms. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I'll admit it's not the most efficient amp on the planet but for size that totally makes up for it in my opinion. Even with minimal electrical like you see here over 3000w at 4.5ohms after rise is still crazy. Besides the fan being a little noisy it's the craziest best sounding little amp I've every tested