Too bad it's so frame dependent, and wouldn't work very well with an engine of any size/power.
and why is this?
it looks like it worked well in that lexus
Well, because the frame has to be exactly where that system needs it to be. It wouldn't work on my frame, and I wouldn't change my frame to make it work on my frame. Lexus has... pretty much the same frame as any other car of it's class, and that goes for all of it's classes.
Or, if you were talking specifically about engines, an engine does alot to a car. If it were a large engine in a small car, such as my setup, this system would probably cause problems. For one, it'd greatly reduce traction (and therefore performance, efficiency, etc), and could cause more serious problems when the engine goes to lift the front wheels off the ground.