I have a 03 Mustang GT Convertible and I want to add a flowmaster muffler. It's the 40 series does anyone have an opinion on this muffer. It's my first mustang and right now it's completely stock but I'm hoping to start to change it.

 

id go with the newer 44 seiries. theyre the loudest flowmaster makes. besides the drag mufflers.

 

I have Flowmaster 40 series and love them. Deep rasby muscle tone, beautiful idle and not obnoxious at high RPMs.
Take note: Flowmasters drone, so I hope you don't have backseat passengers.

 

i have the 40 Series and think their just fine. most folks i've read eventually want to make them even louder, i fell into the catagory.

 

one of those subjective sort of things, can't go wrong with Flowmaster though. listen to a friends car if you can.........