General Rule of Thumb for determining the correct sized tippet in relationship to the hook size of the fly is, "Hook Size divided by 3!" If the hook size of your Stimulator is a size 8, divide by 3, and you get 2.66 which would be a 3X tippet.

If the fly pattern is gets waterlogged, you maybe should try a 2X tippet. ~Parnelli