Brake Squeal (Sprt Pkg)

ukmastermind

Rear Akebono Sport Brakes with OEM pads squeal like screaming banshees in the morning when cold and even when hot (not as loud). I've done the following and nothing seems to work...I'm going crazy..

Attempt #1 (Reduced noise 10% for a week)
-Cleaned dust out of calipers and area
-Sanded down pad surface
-Clean/regrease OEM shims,pins,& Bracket w/ Synthetic brake grease

Attempt #2 (Even louder than OEM Pads!)
- Cleaned everything again
- Installed Akebono ProAct Ceramics
- New Centric Rotor
- Bedded In

Attempt #3 (Quieter for one week, then back to crazy loud)
- Cleaned everything again, Re-Installed original pads
- Sanded and rounded edges of Akebono OEM pads
- Re-greased everything

Attempt #4
- Install Centric Posi-Quiet Pads?
- Keep fingers crossed?

My neighbors '12 G37 Sport Sedan has the same exact problem in the rear and his mechanic says there's no fix.

Any suggestions on how to quiet these bad boys down??
P.S. Fronts are dead quiet, and I have 40k on the brakes so far (60+% Remaining)