Effective or not, I know that I am now realizing 28-29 MPG (since I've added the intake and exhaust mods).

While I'm sure the engine mods do help, the aero of this car is helping out as well.

How much does it affect the overall coefficient? Not sure, I'm no aeronautical engineer. But I just know Steve could tell a huge difference on his as the needle climbed. He not only felt the difference, but heard it as well. And if you can "hear" the air catching on something, it means that area could be smoother (think bad weather-stripping).

Any sport-touring coupe that gets ~30mpg is a freaking winner in my book. That's only 4mpg away from a Focus, and we're a lot faster and better looking.