Any possibility that you're rubbing on the fender at full compression? It looks like you've got some scrub marks btw/ the tread blocks and the Yoko letters. I was running a rear spacer and found out I had some subtle rubbing issues, just on track. Not sure how much lowered you are, just a thought.
2008 M3 Coupe / DCT
// StopTech BBK 380/355 / Pagid RS29 / Motul / Apex Arc-8 / BFG R1 / Ground Control / MS filter / Performance spoiler / BPM tune // Road Atlanta 1:39.70 / VIR Full 2:10.87 / Barber 1:42.20