I think you need to figure out first if its chatter caused by back torque, or just you lifting the rear wheel under hard braking and it chattering across the pavement as it does
My bike has a stock slipper clutch, and I cant make it chatter unless I really try, maybe once in a 100 laps, but there is no way it would chatter every lap, especially at a small track like TMP ...Hard braking wheel hops on the other hand I get all the time...Its normal if you brake really hard and late, and you get used to it even thou in the beginning it feels really sketchy
Suspension would be weird that it only happens in one turn