H&R Super Sports will drop the car ~1.6" in the front and ~1.75" in the rear. Race Springs drop the car less, ~1.25.
I have th SS's, and I love them...amazing stance and the car does feel more composed on the curves. My drop is slightly lower than usual as I took out the isolators...this will make the ride more harsh and louder in the cabin, but that's what music's for, lol.
If you get the SS's, plan on new shocks/struts and CC plates at the minimum.
At 32k miles, your stock parts will last for a little while but will eventually wear due to the changed load and rate given off by the progressive springs.
New ball joints aren't a bad addition and a bumpsteer is a must. It will be greatly exaggerated after lowering and can cause uneven tire wear and an unpredictable car on the road over bumps if not countered.
The CC plates, bumpsteer kit and solid alignment will get your car's geometry back into spec to prevent uneven tire wear and possible blowouts, even with 315's on the back
It is important to to suspension the right way. Just installing lowering springs will only bring wear issues in the future. It's best to spend the extra cash and replace the necessary components at the same time.
You will spend more in the short term, but you and your car will appreciate it in the long run