Problems with EBC Yellow Stuff pads and S8 Brembo calipers

[ur20v]

Howdy y'all... I have a B5 S4 I have fitted with front Brembo calipers from a facelift S8. I purchased EBC Yellow Stuff pads for them, but when I went to install them, they didn't drop/slide in like the Textars that came with the calipers (I bought the calipers second hand). I had to file the powdercoat off the outer edges of the backing plates to get them to fit, and even then there was zero clearance - such a tight fit I had to tap them in place against the piston faces. I double and triple checked that I got the right pads for the application through EBC's catalog and my supplier and they are indeed correct. Now I have noticed that the metal shim on the outer pad on my right side has unglued itself and is migrating toward the wheel hub. I fixed it once a few weeks ago, but it has started moving again.

Has anyone had similar fitment/quality issues with EBC pads and their S8 calipers? Or EBC pads in general?

Thanks a ton!