Glad you enjoyed it. That's an interesting point you raise; the lowered weight can reduce traction slightly. Still, I think that gear setup can fix traction issues for pretty much every car in the game, especially the Speed 12. If you're struggling with the racing modified Speed 12, here's my tune for it:
springs: 3.8 / 4.6
ride height: 85 / 105
dampers (B + R): 2 / 8
camber: 3.6 / 1.0
toe: -0.20 / 0.20
stabilisers: 4 / 4
gears: final gear to 5.500, then auto setup to 4, then final gear to 2.500, then set individual gears to 2.685, 1.955, 1.620, 1.350, 1.129, 0.959
downforce: 0.78 / 0.99
LSD (I, A, D): 30, 30, 1
Max out the rear height if you want, though it'll just make the car understeer more on corner entry. Between 3.5 and 4.0 front camber and 30 LSD initial makes a huge difference for corner exit stability. You can leave Decel. to 1 since the car handles fine entering corners, as the ride height is moving the car's center of gravity forward. The soft springs help greatly on bumpy tracks, the Speed 12 can cruise through curbs and dips (I tested this tune on Autumn Ring, where the second half can throw your car off if its springs are too stiff).
The absolutely crucial thing though, is to never use 1st gear. 2nd gear will be slow enough that the Speed 12 can launch and exit hairpins without kicking out, so drive in manual and keep the car in 2nd around tight corners. Hope that helps out.
