My HDK install thread.

DR HEMI said
Whatever you do in the front shouldn't affect the height of the rear at all.

From what I read, in the front you install the shock simulators and with the wheels/tires you want to run, you set the simulators to one of their three presets which emulate the three most popular shock body lengths. This is the length of shocks you order. Simple.

The spring is then chosen by what lb. rate spring gives you the recommended amount of sag when laden.

That's it. The rear end is not involved whatsoever.

Not so simple wait and see the spring rate is determined by the location of the bottom spring adjuster and distance from eye to eye on the shock suggested by QA1 and yes the rear is involved depending on the stance it has and what you want it to be from front to rear the HDK systems is set up to lower the front so unless you do something in the rear it will have a lot of rake