Thanks for the replies so far.
It's stock pads and sufficient depth per the track inspections. Last fall they were near new with < 6k miles. I recall doing a light bedding in drive after returning from track last fall but each track day has felt the same, no better no worse although a good bedding in exercise wouldn't hurt.
It will probably be spring before my next event so I may look into fresh track pads before then.....
PS: Yes I've gotten on the brakes hard enough to activate ABS at times on track, mostly when miss judging the braking point for a given speed.
PS: Even though I termed it brake shudder, I've had that before and this doesn't feel the same. More like the car is hopping on bad pavement but it's consistent in any high speed braking zone. I have few places to experience it on the street... maybe a nearby off ramp. But officer, I was only doing 100 mph to test the brakes.
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2020 X3M non-comp, Alpine White over black : Exec Pkg, ventilated M Sport seats, 20"s
2020 M2 Comp, Sunset Orange/Blk: Orange stitching, DCT, exec pkg, bicolor rims
Gone '18 M550i, '16 X4 M40i, '15 M5, '13 X3 35i, '12 335is, '11 X5 50i, '09 Z4 35i, '08 550i, 06 X3, 06 650i, '02 M5, '99 540i