I have the K&N FIPK... I got around 17 after installing it with my S/C, and when I first bought it, I regularly stomped on the skinny peddle so I could hear the S/C working laugh . So I would say.... Cold air intake, synthetics, Then maybe exaust. Although, I didn't plan on wheeling mine when I first bought it and threw the cone filter in.... then I went through a creek and soaked it..... sooo just something to think about cool