played with my self level a while back when looking into mv6 suspension and if it would work with self leveling rear end, specificaly just lowering the rear 15mil to match the mv6 front ride hight.
I planned to bend the wire con rod to make it shorter, but first checked the car would drop by that much if at all. Popped the rose joint off the the suspension arm and moved the hight sensor arm down to its lowest position. It didnt drop at all even though the pump did its start up procedure. I tried raising it then dropped the arm to its lowest point, the car just dropped to its original hight, wouldnt go lower.
Basically all the sl does is raise the car back to the correct ride when the rear is loaded, it cant drop the car to a level below that of the springs as they dictate the ride hight. If anything, if you keep those springs, the sl right should be raised to the new hight perhaps? Depends if the new hight is correct...?
So i would guess the answer to your question is no, esp if the new springs are sitting higher than the old ride hight. They aren't sitting down to the old self level hight already, adjusting the sl lower would appear to be pointless i would have thought...?
For some reason i am under the impression tech2 has a setting for self level, it certainly knows if the pump is running too long as it showed the code telling us that i had been playing with it. It thought there was a leak in the air system.
Maybe a tech2 owner will be along.