i am planing on fiting 31x1050x15's on my stock 03 S-10 by cranking the torsion bars using keys in front and using lift shackles in the rear. can someone explain to me how the keys work. should i waste my money on them or not?  

The keys work by turning the attachment point of the torsion bars.  It really just adds more stress to your front end components and CV's.  I don't recommend keys or more than an inch or two of cranking the bars.  

I agree with lwbfl.  You'll be changing CV's more often than you'll like to. Not so bad if you do the work yourself, but it's killer if you pay a shop to do it often.  

im thinking about skipping the keys and just cranking them an inch or less