Brass was 4/10ths of a mm, now 6 to 7/10ths of a mm (someone needs to check this, but this is what I wrote when FP was talking).
He also said that the greater distance between the two helped minimize what he called the “cushion air effect” which was occurring between the two. More distance seems counterintuitive but he does seem to have arrived at the conclusion that further apart is better (up to a point).
He also said that the new movement experiences Resonance faster than the previous movements.