Well the instructions just say "put on the engine mount" more or less. The plans don't show much either. Luckily it wasn't too hard. There is some flex in the mount even though it doen't line up perfectly with the pre-punched holes in the stainless they are all within the diameter of the 3/8" hole that will eventually be there. I fiddled with it as I had it hung from cleco's by safety wire and proped up with some garage furniture and finally settled on where I wanted it. Then I used my buddy Mike's drill bushing that is 3/8" OD and 1/8" ID and that was a life saver! Then I drilled the holes progressively larger until I got to 3/8". The plans don't call for a reamer but I would have like to use one on the last step, but it turned out fine and the holes look perfect. I mounted psuedo temporarily since I will need to remove it to do some of the firewall forward stuff.
Here it is just handing by the safety wire and propped up by drawers.
Looks cool hanging off the front - the airplane grows!