First, cross that header off your list and replace it with a JDM 4-1, a JDM DC 4-1, or other better flowing header with a 2.5" collector. Next, if your stock GSR TB will work with the Skunk2 IM, send the TB to Jorge (The New Spaceballs) over on Honda Tech. He can overbore stock Si/GSR TBs to 64mm at the plate ... he can also do ITR units to 66mm and he also started doing K series TBs. A pretty good upgrade, the turn around time is quick, and it will only cost you $100. He cleans the TB, resets the TPS, and basically makes everything look like new.