Having recently solved my own squeaking brake problem, I highly recommend www.chainreactioncycles.com/hope-tech-3-e4-brake-no-rotor-/rp-prod185567 together with their www.chainreactioncycles.com/hope-floating-disc-brake-rotor/rp-prod145730 (they ship to the USA). I sized up to 180mm rotor from 160mm also. You might already be 180mm or larger.