Finally got the car handling something like what I wanted, but by this point the tyres were trashed (showing canvas). Still despite the shot tyres I managed to set my fastest time of the day a 2.07.6.

Road driven E46 M3 with aircon and cruise ~1460kg with driver
Karbonius airbox
Walton Motorsport exhaust
KW Clubsports
Used (ex BTCC, then 5 trackdays) dunlop soft slicks
K-Sport brakes
Aero