The header is a really good buy, along with the pulley. I also have an auto but you still pretty much get the same benefits power wise. On the header, xaio did put it on a dyno, there are a couple people on here who have bought the header and reccomend it greatly. The underdrive pulley also was proven to gain power, not a whole lot, but it helps in other ways as well, and with all the other minor upgrades it will also make the pulley more effective.

There are a couple of threads on the fourm about the header and pulley, most of what I know as come from what other people have found, I have the header on its way and the pulley sitting around lol

If you want to buy a header, I can get you xaio's email. He is a really good seller, he has been pretty busy as of late though.