To settle this Flowmaster versus Magnaflow debate once and for all I have both Flowmaster and Magnaflow. Sounds pretty good to me. There you go, end of story.

 

"Original" Flowmaster 40 SI/DO here. Not bad sounding at idle, but when I go over 3000 rpm, it tends to get high pitched. Not to much drone in the cab at highway speeds like some have claimed. All in all, it sounds good for a v6.