Based of a new AMC head, L3 head is for a street car / off road car. A increase in power and throttle response. Power output, depending on your combo. New heads castings, valve job, springs shimmed to your cam and rockers. This combo is a stock port ,retains bottom end torque, with excellent mid-range to 5000 rpms and increased fuel mileage. Recommended mild cams shafts and mild list .400 ~ .450 numbers at the valves.