Review on 🚀 Enhance Your Engine's Performance with Mr. Gasket - 8016MRG Tdc Whistle by Jeff Billingsley

The problem isn't the whistle (which works great) or the TDC whistle concept. In fact, the hose is too "flexible" - if you shove it down a deep spark plug well, it just wasn't possible to screw it into the spark plug thread. In contrast, the spark plug air adapter that was part of the leak test kit screwed nicely into the same spark plug wells. I ended up using an endoscope to visually check the OT and now it's garbage. If you have plugs that aren't countersunk this might work for you, otherwise I'd recommend an endoscope or some other way to check the TDC.