Converted to vacuum brakes; can't hold more than 2-3# boost while brake torqueing. My 60' times went from 1.7-1.8 with powermaster to 1.8-2.0 with vacuum. I have S-10 wheel cylinders and two long shoes (Performance Friction) per wheel. I want to try softer shoes with the vacuums before I consider going back to pm and need suggestions on what soft shoes to buy. Thanks.