I finally got around to installing this protective device today. Unfortunatly I discovered a flaw in the design.
I can say that most of you that have installed this have accomplished nothing other than a look pretty or feel good.
The '7mm fastener' marked A in the instruction sheet is threaded into the plastic fuse block housing. It is NOT properly grounded and is used as a fastener for the mac amp. If it provides any connection to ground, it is through the black painted plate and through the body of the mac amp.
In Jay's photos, he has other circuits grounded here as well and one of them may be providing the ground for the circuit, or maybe not.
Anyway, for most of us, if this circuit is going to do anything, a good ground connection near by is going to need to be found and the device modified to connect to it. There are none within reach of the current wire length. If I get the time to tear into it again and do some digging, perhaps I can post back the required changes. Or perhaps Jay has some ideas.
I do not mean to steal thunder, just hope to get this positive idea to provide the protection as it was designed.
The McIntosh power supply casing is grounded - so you could use the phillips screw at the bottom. All the other Torx bolts in the footwell area are grounded. The only thing not grounded was the original screw that was used and the large hexhead bolt below it. If you use the screw at the bottom of the casing on the McIntosh, be sure to use a washer that bites into the casing - because the screw itself is not grounded. The silver Torx bolts that attach the console are farther away - but they would be my choice.