Hey team,
Ive also discussed with Wayne (early last year) and my 2004 donor ABS system is working fantastically in my 818S RHD (by swapping the routing as touchstone detailed above). Only exception for me is I have not used any proportion valves anywhere. Some of us have previously discussed in another braking thread - many mid/rear engine sports cars, have the same big callipers and disks on rear as front. My theory was that we will always need more rear axle braking than the standard 2 pot callipers. Due to my lack of including any proportioning valve - I could have easily used the standard subaru routing - however if one of either circuit from the master cylinder was to ever fail - I personally would prefer to retain either both front or both rear as the second backup emergency stop circuit. With standard subaru 4x4 the LF RR versus RF LR might be more balanced, however my own inexperienced knowledge expects that the standard subaru layout will undoubtedly result is uncontrollable 360 spins if heavy braking was required with only one circuit working?
I still intend to add larger rear disks and add 4 pot WRX front callipers to the rear of my 818 to improve the braking performance overall - still no proportioning valve!