ya it does direct air flow perfectly no mater what. only reason i honestly did it was cause i destroyed it the day before the tune by stepping on it accidently lmao, glad it works without it, also happy you can discuss it without a huge flame war overtaking this poor OPS thread lol.
To the op: YA THE tb's need to been cleaned they get pretty gunked up, more on the other side of the tb though(not the side your trying to get to).