How is PCM getting more hp out of the 5.7 vortec ie. What is different between the 300 plus which has a 600cfm carb and the 335/343/ excalaber which uses fuel injection. Both are 5.7 vortec engines, different exhaust manifolds? different camshafts? I know if you ask PCM directly they won't tell you anything. If it is just the fuel injection flows more air then going to a bigger carb say a 750/780 should do the same thing