It's a few years old but in depth and interesting, one aspect of the build is the fit meant of the K&N typhoon, claimed 30 hp increase ?
@Warrington guy I now has this fitted care to comment mate, what's your thoughts on that figure or am I reading it wrong it's a lengthy article.
Big Rat
http://www.motoiq.com/MagazineArticles/ID/1827/Project-Lexus-IS-F-Part-1-We-Test-the-KN-Typhoon-High-Flow-Air-Intake.aspx