I did some talking with Mychailo about this idea, comparing the basic dimensions of the SVX and Impreza/STI struts. The fronts are roughly the same length, but the rear STI struts are 1.5-2" longer than ours. That in itself is not a problem, a suitable drop spring setup(or adjustable coilovers
) would bring the ride height back to normal. The problem is that the STI has as much travel as we do in the rear. So to drop the rear to normal ride height you would use up 1.5" of suspension travel, giving you less than the SVX has. So, my opinion on the swap as of now:
The STI suspension CAN be used, with modifications.
1. Both front and rear SVX knuckles will have to be thinned somehow to fit into the strut mounting flange. Either by machining or grinding. Or you can pry the flange open to fit onto the SVX knuckle.
2. SVX top mounts will have to be used, or the shock towers in the SVX body will have to be drilled and cut to accomodate the different bolt patterns.
3. A bracket will have to be welded to the front control arms, allowing an aftermarket swaybar endlink to attach to the control arm rather than the strut. A rear '05 Outback endlink works perfectly.
4. The rear STI suspension will have to be compressed. This will sacrifice roughly 1.5" of rear suspension travel. To prevent the shocks from bottoming out a higher spring rate will have to be used. This will obviously have an effect on the handling characteristics.
Cost for this way of doing it: STI suspension+machining cost for knuckles+SVX top mounts+2005 Outback endlinks+bracket+welding bracket to control arm.
The big ticket option: Use a custom machined balljoint adapter to use the STI front knuckle. This allows you to use STI Brembos, and any other BBK for the STI.
Cost for this option: All of option A (minus machining knuckle) + balljoint adapter+STI knuckle and associated parts+Brembos