Supertigre has or had a shorter version that came with G.15s. When used with a bladder with a pressure of about 10 psi, they would abruptly shut off the fuel flow to the engine. I didn't have a problem with the bigger ones. I am skeptical about the resonance idea. I, like you, am too lazy to do any actual calculation to support my skepticism, but I remember the Vibra Tach, a piece of wire with a calibrated slider that read RPM when slid to the wire length that resonated with the engine. As I recall, the wire diameter was about the same as a needle valve, and the resonant length for 11,000 RPM was 3 or 4 inches.