I think the regular one comes with multiple springs, theres is preloaded/ ready for install out of the box. The regular one requires some work .
Also looking at your signature has me a bit confused, WS6 LS1 swap? They came stock with an LS1(current + 8 other LS1 cars under my belt).
You on LXforums? Had a few cars on there as well.( Just sold my scat pack.)