The rear of my S14 has the coils set on the highest setting, and I have 1 fingergap between my rear tire and fender. Exhaust is about 3.5" off the ground
If you slam it, I'm sure you can go really low on these coils.
For max lowering height, you might need to contact Stance directly, because I'm not too sure exactly how low, but from looking it and what my mechanic said, you can go really low. As for the spring noise, my mechanic said that it's the sound of the spring loading up, and he told me Stance coils have a tendancy to make that noise. Honestly, it's pretty quiet and doesn't bother me.