Welcome! I am currently also running the Bilstein PSS9, they are great coil overs, and perfect for a street driven can (the out of the box spring rates are a little soft for dedicated track duty). You can easily raise the height of the coil overs to near factory ride height, I suggest making incremental changes and make the same changes on all 4 corners (same amount of turns to the adjustment for each of the 4 coil overs).

As for correct the snap oversteer, what many have done is to change the stiffer AP1 rear swaybar for a softer AP2 swaybar, that will certainly help and should be a low cost alternative.

 

Welcome, and congrats on the purchase. Bilsteins are an awesome suspension, I would definitely keep them, they are much better than stock. I have the PSS version and I wouldn't trade them for anything as they work so well and offer a great ride.

Snap oversteer just means not getting the car out of balance, don't slam the brakes mid-corner, take it easy in the rain, and do all your braking before you hit any corner, then accelerate out of the corner. I'd recommend the CR front sway bar, it works well on ap1's., I like it on mine. Get the ride height increased, those coilovers shouldn't be slammed, the car will run better with some fender well gap.

 

Smoke another one!