There seems to be a lot of back and forth about Flowmasters installed on the Shelby GT 500. Rumors about a Flowmaster Rep stating they reduce horsepower etc. Has anyone done a before and after on the dyno to actually see the difference of factory mufflers, versus any of the three offerings from Flowmaster for 2007-09 Shelby GT 500 If so, please let us know on this forum. NOTE: I have submitted a trouble ticket to Flowmaster and willl post their response. Thanks!
