I've now covered about 10.000

miles in the last 15months with a stock 3/4" bore m/c and 951 Brembos F + R. The bias feels right, the braking is phenominal. Nothing but.
The mathematics may well suggest a too forward bias, my front wheels are 95% of the diameter of the rear. Which helps brake bias no end. (I've had bigger tyres on the rear of 4 out of 5 of my previous Bugs)
What is the diameter of the equally sized pistons in the rear callipers and the diameters of the two bigger, dissimilar sized pistons in the front?
I'm not convinced I need the Kerscher split-bore m/c. And I don't want to pull my callipers for such a trivial task, needless hardline fatigue and all that.
Matt