The Mustang rear suspension is definitely lacking, as is the whole fox platform honestly.May I ask, why spend effort and $ on the front suspension when the fox/sn95's weak spot is its rear axle?
The front strut design is fine for a street car, and can be modified to work pretty well for handling. But the short long arm design is one of those "have your cake and eat it too" situations. There's very little compromise with the design.
The car in question already has the whole Maximum Motorsports catalog on the rear axle, which works exceptionally well.