BTW, I think this is part of the issue though I am pretty sure I also dremeled my Stoptech pads slightly, Stoptech pads vs others:
Stoptech ST40 Pad Dimensions - width of backing plate is 131.8mm
Pagid 1204 Pad Size Dimensions - width of backing plate is 132mm
I think most of the pads we are buying have ~132mm backing plates and the ST40's are designed for slightly less, IMO, YMMV, etc.