My 1303 just got a step closer to a GL

[evilC]

For the bias to be 50/50 (ish) the hydraulic advantage should be the same front and rear i.e. the total piston area at the front divided by the master cylinder piston area should be the same as the total piston area at the rear divided by the master cylinder piston area. With the 944 or any other Porsche combination the front and rear rotors are about the same size so that any mechanical advantage is cancelled out, which makes the assessment easier. The stepped piston m/c does give an ability to adjust the bias but not much. The difference is that the piston areas are 529 sqmm and 361 sqmm, which is usually not enough to account for big piston areas at one end or the other.
IIRC the 944 front single piston caliper is 53mm dia (2809 sqmm) and the rear single piston caliper is 36mm dia (1296 sqmm) therefore, the front piston is 217% bigger than the rear that can't be moderated by the stepped cylinder because the variation on piston area is 'only' 146%. Basically, the 944 single piston rear caliper is too small for just about all variations of brake caliper on the front. A 25/17 stepped cylinder would work but they are not made as far as I know.
Whilst having the fronts lock first is the safe mode, if they lock too early then you will not see maximum braking from the rear.

Clive