My disc kit is the same, 3/16" line with 3/8" 24 fittings and I too am not using a booster. My current drum set up is the same line and fittings aside from that first section which is the 1/4" with 7/16" fittings at the MC and that first block. My new residual valves are also 3/8" 24 fittings for a 3/16" line.
I've never had any issues stopping with the current set up even with the mc almost dry it still manages to stop pretty well. lol.
