To move the snap-ring, just push the end of the ring out of thee groove w/ a screwdriver and move it.

My car sat higher in back w/ stock suspension, so I figured that it would still sit higher in back w/ H&R springs (1.8/1.5). I was right. After driving on it a week w/ the perches at stock height, I dropped the rear perches down for an extra 5/8" drop. My car sits nice and even now. :thumbup: