Hey guys...first time posting on this forum. I have an 04' FX4 and want to put a dual exhaust system out the back. I was wondering if anyone has any experience with the American thunder with the 40 series. If so..how does it sound/perform. thanks

 

I have a 1999 F-150 2wd 4.6 V-8 with a Flowmaster 40 series on it. The truck will gain some power, enough for you to notice. I got 1 mpg better around town. Many people will tell you that they are too noisy inside but you must remember that your exhaust tips will be over 6 feet from your cab so it will be much quieter, just turn up the radio.