[creeper]

before reading please note that i am not always a "Strano nazi":

BMR revised their springs and copied their spring rates from Strano (they're almost identical). smart from a business standpoint, but i personally will not support them simply because of that. vain? possibly. but bigger companies copying what others have done and trying to do it cheaper bothers me. Stranos are only a tad more expensive ($275 shipped) and weigh less (no big deal but it can't hurt). BMR/Strano springs are linear, which is better for handling, but may ride a little stiffer.

If you go with the prokit, I would recommend the LT1 kit. they have "better" rates than the LS1 set and the rears don't sag over time.

relocation brackets are up for debate. none of the springs you're considering have a super high spring rate in the rear like most other sets so launching probably won't be too bad. when i had stiff springs in the rear i definitely needed them. now i have softer springs so i'll probably adjust them to the middle hole or remove them altogether. we'll see. get the springs first and then see if you need them.

also, i hope you're planning on/have good shocks too