There are alot of mods i want to do to my focus (radio,headlights,body kit,etc), but im not sure which one i want to do right now. This one seems like it work best because it slightly increases gas mileage (to my understanding) as well as give the car a tad bit more power, so it seems like in the long run it kind of pays itself off. My question though is, is it worth it? I like pounding the gas and hearing the engine roar when accelerating and such. But asking those who have done it, is it worth the investment?