I liked mine just fine, was a bit of work but the effort was worth it.
Here's a pic so you can see where I cut the slot better
To stop the radio from switching itself on do this to the main board
Also it's not clear in the pdf but one of the boards at least needs soldered on both sides and also use a decent length of wire between them. It means you can set all the clock etc then tuck the middle board with the buttons between the HU and the main box to get it out of the way.
Finally this is another spot people fit them in the Mk3
Just take a live and negative and extend the speaker wires