Any engine can have a tuned intake and/or tuned exhaust. Mild timing and mild valve sizes will only lead to mild response to the tuned intake. Just because we don't see many on model airplanes doesn't mean it doesn't work. Virtually, every production automobile engine since the 90's has some form of tuned intake, although we in the US were a little slow in the game.

I've caught a few posts here and there about a guy who builds Honda GX engines. What do you use them for? Does he have a website?

You can only teach somebody what they are willing to learn.

Greg