The stage 3's are a completely different port design than the stage 2's and have the larger 2.05/1.60 valves instead of the 2.02/1.57 valves on the stage 2's and the 2.00/1.50 valves on the stock heads. We are installing these as we speak on a stock block 5.7 car along with the 5.7 race warrior. We also have these heads on a 392 shortblock courtesy of Daddy Kool. This weekend we are installing a set of the stage 2 heads on a stock block car and then next weekend the stage 3's are going on another car with a 392 shortblock. We will have lots of results from these heads within the next 2 weeks. The last picture our first set of results with the stage 3 heads and a 392 shortblock along with 392 race warrior cam.