It's a SD performance top end, 305 CFM D port heads, old faithful 2.0 hydraulic roller cam, ported intake and a Butler 4 bolt forged short block. We were a bit set back with the numbers when it was ran. Butler was thinking 525 - 550 hp and we blew that out of the water. With a intake swap to a single plane it will make 670 hp but this is already a bit much for the 73. I was honestly considering selling it because it's a bit too much for my car.