my thoughts on leader # test , is that you should use the lightest possible , especially when water is clear . With good knots , proper drag settings , and a skilled fisherman you can land a fairly larger fish than you may think on a light 6-8lb leader . it makes it more fun too , since it is more of a skill thing . Rather than just towing a fish out with a 20lb+ leader . But if you are targeting big springs in fast water than yes use a heavier leader 12-15lb maybe . but I may be wrong . each choice has it's ups and downs . a lighter leader can lead to more lost fish , and lost gear . but a heavy leader may result in less fish , but never loosing gear . I personally use a 6 or 8lb leader when targeting coho . but if i feel that i wanna have some fun with a few springs I switch to a 12lb leader . on 15lb main always . and that is Maxima Ultra green line .