if u go lower then 1.5 inch, get a camber kit.
there is no universal pre side ride height setting on the ss or any coilover setup, even in that tein manual. its just an starting point. you have to play with it and adjust the height and dampening to best suit ur needs. everyone will have a different setup best suited to their needs and comfront. so ur mudflaps r rubbing, raise it, too high, take them off and lower it.

if your alignment is off, you can wear ur tires out quicker with uneven thread wear.