I bought this hoping to get better gas mileage, and a few of the reviews stated it wasn’t nearly as loud as they wanted. I can’t comment on improved MPG, the car was only done last week. It isn’t “loud”, but it does have a nice rumble when getting up to speed, and it doesn’t drone when cruising. The pipes really improve the look of the back; love the oval shape. So far as increased horsepower goes, I’m not a pedal to the metal type of driver. It seems to have a lot more power, but that may be because it sounds like it. My mechanic said this is not only the best quality after market exhaust system he’s ever installed, but by far the easiest. I’m happy with the purchase, and so is my ’03 T-Bird.