Just had a quick go at this as last time I got gold I used standard physics... got gold at the 3rd attempt, but this time using pro (1'13.993).
Few hints...
The M3 doesn't like to turn and brake at the same time, so make sure you brake early and ease off the brakes when you turn in... you can only be on partial brakes (<50%) whilst turning.
Take all of the the fast right left in 4th gear, and brake gently/ease off early for the left part... maximise you exit speed, not your apex speed (aiming to get under 11.00 for T1).
You can brake quite late for the corner after the tunnel - change down to 3rd and make sure you ease off the brakes before turning for the 1st apex, then coast out wide, wait for the nose to settle back towards the 2nd apex and pick up the throttle gently... you needn't be on full throttle until almost the fence on the outside.
Brake early for the corner at the bottom of the hill and make sure you're off the brakes before turning hard for the apex... if you do this you can get the wheel straight quickly and be back on full throttle quite quickly. This is the trick for the next 3 corners... ease off early, let the nose get to the apex without applying too much lock and understeering, then get on partial throttle early... easing on more gas as you wind off the lock.
The final corner should be taken in 3rd and treated as one long corner... brake hard for the 1st apex, ease off before turning, and let the car ease out wide and settle back on line for the 2nd apex... then pick up partial thottle, increasing the gas as you wind off the lock.
Good luck 👍
EDIT: Just tried it in standard (1'12.343)... same principals apply, but you can be much more aggressive with the throttle as there's a load more rear grip.