K&N Cold Air Intake Kit: High Performance, Guaranteed to Increase Horsepower: 50-State Legal: 2005-2006 FORD (Mustang GT)57-2565

I bought the FIPK Gen II for my wife's '06 Mustang GT, simply because I love the snarl of low-restriction breathers. The 15 hp?  Yeah, OK, like I'm gonna really feel it, if it's even there. Funny thing is, my seat-of-the-pants meter really did pick it up, even through the hype of that terrific growl that always makes you THINK you're accelerating faster than you are. But that's not all. The Mustang has an on-board mpg gauge, and two days after installing, my practical-minded wife asked if it was possible that the FIPK could give the car better gas mileage.  To make a long story short, we have checked this out a couple of times, and on trips we have always gotten about 24 mpg on, we are now getting 26.5 mpg, driving the exact same way. And yes, that's the V-8, 300 hp GT model. And no, the old air filter was not clogged - it was in very good shape. I'm always cynical about manufacturer's claims,and maybe not all GTs will see this improvement, but the on-board computer doesn't lie. This FIPK will literally pay for itself in the next few years. I'm a satisfied customer!