I think an angle mount makes the shock softer than the same shock mounted verticle. More angle means more soft. I use to run mine at 15 degrees plus they were in front of the axel. In front of the axel required a stronger spring plus the shock was extra soft. JMO, RM
think of the suspension as a bar hinged on one end and the shock/spring assembly is on the other end 90* to the bar , it has 100% effectivness any change in the angle of the shock/spring assembly lowers the effectivness
I understand the the back to front angle, but what I am referring to is from side to side.
If you were standing at the back of the car looking at the rear end.
I have seen some mount the shocks at a slight angle (Tappering out from top to bottom).
Is there any reason as to why this might be done over straight up and down?
look at it the same way any tilt in the shock will reduce its effectiveness, side to side or front to back. tilting the shocks (a small amount) is common practice for some builders just for packaging, nothing wrong with it and actually has gains on lightweight cars.