I just installed an Isspro 2-50 mechanical boost gauge, plumbed with a piece of 1/4" rubber hose to the manifold test port. When the engine is under load, pulling about 16-17 psi, the gauge makes this sort of buzzing noise and the needle flutters a little. Is this a bad gauge, or does the pressure fluctuate when the waste gate starts to open, causing the gauge to wig out? It seems to work fine, it's just an irritating sound. I can always turn up the stereo if I have to.