it really depends on what you like. My opinion is a 12" 250lb coil is a good all around rate. I used to have a set of 12" 350's and loved them. Right now I have 14" 175's and they are waaay to bouncy for me. When I get around to swapping K-frames again (to a PA or Griggs setup) I'll probably go back to 350's or 300's. You can get QA1 springs from Summit for like $32 a piece.