I said it totally wrong.....meant to say the very outside top of each mirror works best, not the inside bottom. But hey if it works for you that is all that matters, maybe give it a try the other way for comparison sometime.
I've tried them on the outside edges (where IMHO it will cover up usable rearward OEM mirror visibility) of the mirrors and several other locations on the mirrors as well. For "me", the inside and upper edge works the best. In that location prior to installing the auxillary mirrors I would only be seeing my hands on the grips (not something that I felt was usefull to be vewing as I ride). That's why I located my auxillary mirrors in the location that I did.
Different riders will view their mirrors differently, so to each their own. I'd suggest that each rider should locate auxillary mirrors in a spot that will provide them usable rearword viewing without reducing the usable view of the OEM mirrors.