They were originally invented for engines with carburetors. They bolt between the TB and intake manifold -there are claims that they increase air volume / change air flow patterns to increase hp, torque and mpg. To me they mostly sound like garbage "cheap hp" mods. In truth I think they can be effective on certain applications, of which ours is probably not one.
edit: If you wanted you could just leave your TB heater plate in and it would work just as well...