theres a few lines that go to the evap canister (in cali, the vapers from gas have to be nuetralized, so the vapers are ran threw come type of coal or something to do that). and maybe something else. again, i did my tank at the same time so i dont know for sure if it has to be capped.

 

There is a thread here, or on thumpertalk that shows removing it. I cant remember who's site but it did a good detail w/ pics too. Don't know that it addressed any performance gain though. Welcome to the forum.

 

The 2009 has a cat? Where is it, in the canister?