This set up is really only suitable for measuring oral cavity pressure during a steady sustained note. It takes a couple of seconds for the liquid levels to stop bouncing around and settle. I only have my own data to go on, and I play all my sustained notes (at least to high C) with a low tongue. For me, raising the tongue while holding a steady pitch does not affect the pressure measurement, though it does 'tweak' at my embouchure and alter tone a little. If we had data sets for some players who habitually use a high tongue level for sustained notes in the upper registers, then we would have something to compare. I have a hunch as to what we would see, but it's only conjecture at this stage so I'll keep my hunch to myself for now. I did try warbling a few lip trills for interest. The notes are too fast for the manometer to follow, but for a lip trill E-G the indicated pressure settles at some 'weighted average' level that's a lot closer to the steady G mark than the E. There doesn't seem to be that much in it. I've just done a quick check and for a high G, the Wild Thing seems to take a little (maybe 10%) less lung pressure than the mouthpiece alone to hold pianissimo. As the volume goes up, the difference magnifies exponentially: there's no way I can manage even a decent forte on the mouthpiece. I suppose that's where we get the leverage from the instrument's resonance. No, I've not looked at flutter-tonguing yet.