Thanks for sharing your experience with the GY6 springs. I like the jammer as well, used it on both my 45mm alukit with both the light and medium springs, and the current 47mm Gilardoni setup with both the medium and heavy. Currently using the heavy springs it comes with, but feels like it wants more. I want to could get rid of at least some of the lag when it shifts to second and comes off the pipe, since it fully engages around 5500 with the stiffest springs and I really need closer to 7k for optimum performance with my pipe and jug combo.
Gonna try the white GY6 springs next.
If you have a tach, can you guess about what RPM they fully engage?