I'm not personally fond of the extrude hone procedure and it's "benefits". We've used it a few times on different motors and did not gain anything appreciable that makes the cost of the process worthwhile. I too agree that ceramic coating the intake plenum will yield greater results. Doing so has for me in the past on many aircooled 911's
Second a perfectly smooth surface doesn't help flow any and actually hurts it in some cases due to the loss of the boundary layer(layer of air that "sticks" to the inner walls) Air flowing across a perfectly smooth surface vs a boundary layer has greater friction, this has been proven time and time again. Adding the ceramic coating inside the manifold would most definitely yield a better surface than the super rough OEM surface, but not as bad as going with an extrude hone that damn near polishes the inside. I think it's one reason why the extruded hones DON'T make any appreciable power, at least in my experiences.
And finally, I'd leave the TB's alone. They'll flow more air than the motor could ever really need right now. Only thing I'd ever change would be to convert from a butterfly setup to a flatslide valve setup to eliminate the air obstruction of the butterflies and shaft at WOT but even that's going beyond what most would ever really use.
