Hi Cracksta, I am thinking of same in next couple of months. Basic difference between F sport intake and K&N induction kit is that F sport including IS250 OEM intake aspirates air from the front side of vehicle, while K&N aspirates it from engine space which is obviously warmer, so it might worsen performance. I checked on youtube and both of them make nice change in a sound. Either here and on US forum were controversial opinions regarding K&N filters, they are moisturised with some oil which can be sucked into engine ane make a damage over long time. Stanadrd filters are not that expensive, I have changed it last month and noticed improvement in consumption around 5%. I would probably go for Fsport kit.