Ok i tried to get valuable info on this ? from another thread but everyone wanted to flame some guy so here goes again. do rear bumper air defusers accually work? what was the drop in qtr mile times after doing it? and does this only work on fast cars or will it help a 14-15 sec car???? thanks in advance

 

No expert, but I'm gonna say no on that one.

 

proly .005 of a second rotfl

 

They help your gas milage on the highway