Shock Question

[millzy]

Looking at the x6 set up on 2wdrc I’m happy to see that there is a losi AE and Koysho piston spring and Oil set up listed.

My question is regarding the shock length and shock compressed length- what point is this measured from? and also how are do you get a compressed length of 67.5 on the rear with AE shocks? do you need losi shock bottoms to achieve this