From a fluid dynamics perspective, I believe increasing the bore of the master cylinder would work against you. The better braking effect of the bigger brakes comes from both the mechanical advantage of the larger rotor diameter, but also from the hydraulic advantage that the master cylinder provides by pushing fluid into a larger chamber volume within the caliper pistons. Yet the only cost is slightly more pedal travel. Ergo, the larger brakes generate more force for the same for pressure on the pedal. A larger master cylinder bore would slightly reduce the pedal travel while reducing or negating the hydraulic advantage. The net effect would be the need to increase foot pressure for the same stopping power.Gathering parts for this swap right now, has anyone upgraded master cylinder with this kit? I am a bit concerned about fluid flow/ quantity with upgrading to six piston. If so what Master cylinder did you use? Also is hydroboost a possibility? I have seen mixed reviews. Currently running a cam and procharger so I am a bit concerned with vacuum.