Anyway, watch his videos and see how he went about figuring out where the air was, where it wasn’t and how he got it to do what he wanted. He did damn good work and anyone can learn some things from him.
Greymouser7, I totally agree with this . Watch them over and over, and listen to him thinking out loud.
I'm no pro porter, but I think the only mistake he thought he made was getting involved in the project!
But seriously, I think he was referring to when he first did those heads years ago. I think as he went, he realized, those "mistakes" weren't really that big an issue as he was still removing and reshaping the port, chasing the flow. He just worked out where he only really needed to remove metal and applied that to the second port.
I'm not sure if he's going to use the floor wing or not, so I guess you could class that as a possible, mistake.