I have a TB and an Intake Manifold Spacer. The particular TB Spacer I have Was so negligable on the Dyno (+- 1-2HP), that it's inconclusive on the Dyno tests.
Fuel economy, I dont see how honestly. You're just adding more space for Air to travel to get to your Manifold.
The only thing I got mine for was the Extra heal shielding that it provides. (I have Flex's 3/8' Phenolic Spacers (both TB and manifold spacers)).
I feel that the Intake Manifold spacer that supperates the upper and lower manifold hold the main benifit. V6 Power says they are a waste of time, but I feel that they're worth it, and There were dyno's to prove it.
This isn't ment to knock down your idea. You have a viewpoint, and I will be willing to hear what you have to say and take it into account with an open mind.