Sorry but I do not think so the gt40p's are ok ported but the cooling with the aluminum and better flow path larger valves would allow even a stock 5.0 breath and not hurt drivabilty. The intake velocity wouldn't slow much to affect torque. And the adition of full roller rockers would free up some aditional power. I would imagine as much as 20-30 hp gain over fully ported gt40p. IMOI talked to my engine builder and he said he thought I was better off with ported gt40p's. He's a family friend and said he thought I'd have a better street car with him just doing some work on the heads and the upper and lower intake.