Another reason for changing struts is the fact that the ae86 stub axles are weak. The ra40 ones are far stronger and their wheel bearing is the same as a commodore which makes it easy to find parts.
NoPsi
Well the AE86 stub axle is not exactly made of wood and is quite up to the task of bearing bigger brakes. The RA40 ones are slightly different but 'far stronger' is debateable.