so im about to start my short stroke conversion and i had one question, do i need to remove 40mm from the strut casing? ive heard different numbers ranging from 25-40mm

it mostly depends on the insert you are you using, and which strut you are trimming. a good way to do it is to measure the factory strut, and measure the new short strut, and trim the difference from the strut housing. That way you get a perfect fit.

I'm using a Sw20 agx