You aren't alone...mine flares a lot, and neither the K1 install nor modulator adjustments nor switching to synthetic fluid solved the problem. So my backup sits quietly in the garage awaiting a future swap:

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car