How does it affect DD handling?
Gurus chime in...

 

pointless mod unless u track the car and hit speeds of over 80 mph for periods of time where its actually functional.

 

Even then, its really only functional on cars that are aero/tunnel tested for true results. Newer cars are starting to use active dynamics (such as closing front grills, raising rear spoilers at specific speeds).

If you think throwing a APC spoiler/canards/splitter on your car is going to give you more downforce, maybe you should start with the best tires you can afford, and dropping the car from factory heights. "Downforce" is probably the last thing on a "regular" person's list. Putting stuff on your car like that, that did not come with it (ie: Anything high end and fast / semi-exotic/ exotic) is probably going to screw up your aero rather than help it. They use it in racing applications such as Nascar, F1, GT .. but not for driving to best buy and walmart.