Why the Holes on bumpers?

[Accord9400]

OK i HAVE A QUESTION WHAT EXACTLY ARE THOSE HOLES :rolleyes: (ABOUT 3" DIA.) THAT PEOPLE ARE DRILLING INTO THEIR REAR BUMPER FOR I MEAN WHAT EXACTLY IS THE USE OF THAT ONE TIME I SAW A HONDA DEL SOL WITH THE SAME THING BUT OVER THE HOLES IT HAD SOME KIND OF CHROME PLATE COVERING THE HOLES UP WITH SOME TYPE OF WIRE MESH WERE THE HOLES ARE ANYWAY IVE BEEN SEEN ALLOT MORE OF THAT DRILLING INTO THE BUMPER AND WAS WONDERING IF ANYONE OUT THEIR KNEW WERE THIS IDEA CAME ABOUT OR IF IN FACT THEIRS IS ANY SIGNIFICANCE TO THIS HOLES PLEASE ADVICE ( I SEE THEM OUT HERE IN PHX ARIZONA IF ANY ONE KNOWS WHAT'S THE PROPOSE OF THEM ARE PLEASE ADVISE OR IF THEIR IN FACT THEIR IS PLATS THAT GO ABOVE THE HOLES PLEASE NAME SOME WEB SITES OR SOMETHING THANKS HONDA FREAKS!

[whoaitslen2]

http://164.109.57.200/images/LSTRDiffuserspair.jpg

They are a type of rear air diffusers. They are just holes drilled into the rear bumper cover to vent out air at high speeds. During high speeds the rear bumper cover acts like a scoop and creates drag. Top draggers and road course racers usually just take off the rear bumper to eliminate drag. These rear air diffusers were once used for functional purposes in the beggining of import drag racing until racers started to just take the whole bumper off. Now theyre widely used for just show purposes.

[Accord9400]

i get it now it makes since hey i appreciate your input on the subject and helping me understand, one more question though what exactly is the name of those face plates you put on the bumper to make it look nice or is the style to just have the holes on the bumper and thats it or what just trying to understand how to do it if i really do think about doing it, it looks cool and i think it looks nice for show!

once again thx for you input bud!

[whoaitslen2]

If you go to a shop ask them about rear air diffusers made by STR.

[Carreragt2e]

Anyone got pictures of airflow around the car to explain t his better. Im kinda lost on the whole take the rear bumper off to eliminate drag.

eric