The E46 BMW M3 was the last of the great inline 6 BMW motors. These cars were light and nimble and a blast to drive. At our altitude they don't have quite enough punch. We went for the Active Autowerks stage II supercharger system to help wake it up. Of course we put our modifications on it. We built a cold airbox for it. The Active kit had a tube coming from the brake cooling duct and directed air to the air filter. We built and enclosure for the entire system. We saw a 17 whp difference with our box. This E46 turned out great.