ok im new here. what do you mean a 2 piece rear bumber air diffuser?

 

yes exactly

 

it is a cut out with 3 holes on each side of the license plate to reduce Drag. The company that makes it is AC autotechnic

 

thats part of one..on the red one..i'll do some more hunting. btw that pic is from a g2ic meet in ny.

edit: more pics....

http://www.g2ic.com/forums/showthread.php?t=109082&highlight=air+diffuser

 

Even though they label that thing as a "diffuser" it really isn't. Here are some examples of a true functional diffuser:

RACE NSX

STOCK NSX

Side profile NSX

Side profile G3 INTEGRA

one thing you should notice in each diagram is that the diffuser isn't the only focus of attention. To make a true functional aerodynamic package, all parts much work together with one another. Its the exact same thing as lego block building an engine. If you don't do it right, it won't work right.

 

on the pic of the white G2 i dont see anything

 

its there on the red one..the one below it is the same car, that was the first pic i thought of when i saw your post. its hard to see, but its there on the red teg.