Took our 818C out for its maiden track day this past weekend. It's running 235/255 Dunlop ZIII tires, no front sway and 350/350 springs. I thought that would be reasonable in view of what people have been running rear spring wise on the forums.

Boy was I wrong. The car was pretty menacing to drive in lower speed corners. It has a bit of high-speed push, but the snap oversteer in the low speed corners made it unnerving to drive, borderline unsafe IMHO. Perhaps more relevantly, overall grip in the low-speed stuff seemed to be way down. We were crawling through steady-state corners compared to other cars.

We dialed in rear toe during the day to try to improve the situation, and it helped a bit (now running 1/4" total, maybe a bit more). I think the rear ride height is too high vs. the front, but wouldn't think that would make a huge difference.

My first thought was to try the stock rear springs, then again, many seem to be having good results with higher rear rates.

Up the tire stagger? Add the front bar? All of the above?