This installation drawing from Simpson addresses this issue.    My understanding is that the occupant must be held in the seat.   With some current shoulder straps going up and away to the top of the fuselage, any large-G upside down hit will have the pilot potentially going through the canopy with stretch and flex

The Legacy backrest is almost the right angle.  I have to check to see if it is more than 10 degrees below the shoulder.  If it is, I can easily add a spacer to the backrest to bring the geometry to 10 degrees.   My crotch straps are not installed this way, they are both back to the lap mount but I'll look to see how the geometry might be optimized.   Graphic from Simpson's website.

Paul

Gents,

 

The shoulder strap ends should not be mounted lower than one's shoulders as this could cause a compression of the spine in an accident.

 

Grayhawk