Hello, I was a beta tester and found this to be the most simple and reliable way as pictured below. 1st mark the half of the cyl. magnet that illuminates the green LED's on the twin sync unit, and mark that half. That will be the half that faces OUT. Then you can use 3/8" square hardwood stock or 1/4" ply ( NOT METAL or carbon fiber) to bolt to the bottom of the engine mount. Then epoxy the hall sensor to the wood with a 1/16" air gap between the magnet and the hall sensor face with the writing on it. 1/4" ply ensures that vibration will be kept at a minumum. This method works with magnets in the spinner backplate or in the prop driver (hub). This is MUCH better than trying to mount the hall sensor to the cowling (NOT recomended). Hope this helps. Rick Simmons