hello!

My approach with the setups is to find the best laptime possible whilst staying somewhat driveable if not perfectly driveable. It's a slightly more agressive approach than Nils' setups.

"This text will expand as we learn more about the car and of course the setup and laptimes will get more updates.

Mustang (general info)
The car seems to follow what we know of the M4 by fair and large, has the same spring sets, responds similarly aerodynamically, steer ratio seems the same, so I guess we can carry a lot of things over. The dampers seem different though, so there's some more to find out.

Engine wise: long rpm range, you want to go near the limiter (shift 8100-8200), which means not shifting into 6th most of the time. This also offers a few situatons where you dont have to shift at all, whereas other cars have to go up and down between corners.

Short shifting isn't too beneficial, as the power really only comes alive in higher rpms. Though it can help out of slow turns where grip is scarce.

The car has pretty nice TC. Even with TC1 on 2 it barely engages when unnecessary, but it will give you a lot more confidence. So don't shy away from running TC1 on 2, 3 or even 4 in this one, and also cranking up the TC2 setting seems to make it smoother and more reliable.

Driving
You can drive this like any front engined car. Trail the brakes deep, aggressive throttle in fast corners, but you need to progress a little into it out of slower turns as the torque can be a bit much for the rears. The speed of your steering input will play a role in wrestling the car around in fast corners where it tends to be very stable. The gear shifts are rather harsh on the car, make sure you are not shifting up when the car is in a already sensitive situation." 

Notes for RBR:

Traction is something to be careful with. You'll need to be very aware of how the car behaves out of the slow corners since the rear can snap out and the end of the first gear or even the beginning of the second gear. I suggest using 1st gear just for T2 and T3, everything else is 2nd. Well, the second to last turn is actually in third (:
Stability wise, you should have no trouble in sending this absolute beast in any corner. 
Have fun!

Adjustments
You can still add more oversteer here by:
- add rear ride height
- stiffer rear anti roll bar
- less rear bump stop range
- more front bump stop range
- less rear rebound damping
- less front anti roll bar

or make it more stable:
- less bump stop range on the front and more on the rear
- stiffer front spring
- less rear anti roll bar
- less rear ride height
- more rear rebound damping

Do one or two clicks at a time. All of these settings will have side effects in different situations.

Any questions? dm me on Discord or tag me in Nils Naujoks' Discord : Stitch5yy024