Correct Way To Install Sfc?

What is the best way to install sfc? i've heard you don't to jack up one side at a time cause it flexes your chassis and i also heard not to use a two post lift where all your suspenion is at full drop. so how do you install then?
And i just installed some lowering spring 1.5" it rides great but when i hit a good size bump or pot hole it sounds like metal hitting is this normal or should i get it checked out? i also have 18' wheels that are tucked real nice has anyone ever had this problem?

A drive on rack is the best way to do it because that allows the car to sit as it normally would no unnecessary stresses. The next best way would be to use four drive on ramps for just make sure your car is on level ground by opening both doors and using a bubble level on the door sills. If you don't have ramps you can use four jackstands again use a level on the rocker sils to ensure that the car is square.

Try this (http://www.bmrfabrication.com/instructions/sfc001.htm)