They will lower the back end a little bit. Not sure how much, but maybe 1/2". This also impact the linkage geometry and how the rear shock acts. They are really the poor man's way to lower the rear end. If you really need to have the bike lowered the best thing to do is have your suspension tuner lower the bike correctly.
I used to run 126mm links but had my bike lowered the correct way and wish I had done it from the start.