From my experience adding lift in general is a no no. I used to have a hot rodded 84 Ford LTD. I didnt add lift but at steady speeds above 90 or so the steering would become very light and you could feel the nose up attitude the car was taking as It tried to push its brick like body through the air. High HP V8 with the stock 6cyl suspension. Lesson learned it made for a very unstable ride. And yes with enough power a cinder block will fly but that becomes more a function of thrust to weight rather than aerodynamic lift if my thinking is correct.
