I just installed the same combo, i have an 07 coupe 5at and when i removed the oem air box there is a plastic bottle looking piece below that seems to be bolted on in 2 places... what is this for and can i remove it?

 

That's just another box to reduce noise. It's easy to remove. You can remove it from the top (harder) or though the wheel well (easier). Just pull back the plastic fender liner.

Your not going to gain anything from removing it.

 

why don't u go with a CAI ???