let's not get picky about the vernacular. Weight and down force are the same thing. weight is the down force generated by gravity. the wing generates down force measured in lbs on the tires generated by the moving air over an inclined wing. and yes lead blocks would do the same thing in the trunk. unfortunately in order to have the same effect as a movable wing or in fact a fixed wing(ala srt-6) you would have to throw the blocks overboard every time you stoped and then pick them up again to generate down force on the driving wheels when you started up. Ever see blocks or sand bags in the bed of an empty pickup truck? It's because there is no weight on the rear(driving tires). the cab and engine are mostly over the front tires. there is not much rear of the rear wheels in the xfire. Now the term down force in race cars is a different matter. The shape of the underside of race car actually generates sort of a vacuum (measured in lbs)which holds the car down. We don't have that on the xfire.