Faraaz23

So I've been searching for a while about these. The HD's I order came in and I'm having them installed Friday, I haven't opened the box but from what I understand the shocks have two different settings for the spring seat.

If you lower the car even more using the lower perch setting, does this compress the shock more at rest (like when you use a shorter spring) or does this lower the whole chassis in a way that doesn't make a difference in shock travel? I'm going to also put on NF210's by the way...