Thanks for the write-up. I looked into K-Mac camber plates last year but decided against as I'd heard repeated stories of their customer support being dreadful, and the components not being particularly good quality. It sounds like you've had a better experience thus far.
Being able to get to -1.8 is a good result, and pretty much exactly what I've opted for using Millway top mounts (-1.75). Being able to keep the OEM top mount means no increase in NVH; a big plus point.
One thing that I've noticed in favour of aftermarket top mounts is improved damper response due to the lack of the OEM top mount compliance bearing. Have you had the chance to compare ?
The K-Mac camber bush looks to be a good product - presumably no need to change any other components. Good find
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Current : F31 330sD, remapped, Ohlins Road & Track, Millway camber plates, Quaife LSD, Stoptech brakes + Pagid RSL1 pads all round, Weichers front strut brace, Eibach front & rear anti-roll bars, Michelin MP4S.