Are there anti-squeal shims available for the rear pads? since I fitted the larger grooved discs mine will squeal a little at low speed. As soon as I put my foot on the brake it stops.
I had a similar problem a while ago, so fed up with the squeel I made some shims, and they didn`t help at all, in the end I removed them, and cleaned off the copper grease and the damned squeel dissapeared.
It's almost as if they require a residual pressure valve or a bit of spring steel behind them.