I have a 2008 Mustang GT and I put flowmaster mufflers on it, but it still don't give me that heavy throaty sound I like. Do I need to change headers or a complete muffler system, if so what brand?

 

The mufflers hold some of the sound, but really the catalytic converters is what holds alot of the sound in the car. You can go with either and Off road style with no cats (wont be legal in any state and if they do emissions testing in your state don't bother) and you can go with highflow catted pipes. Both will make the car louder and deeper if you stay with the H pipe style mid pipe (the part that connects the stock exhaust manifolds to the catback). But the O/R pipe will be much louder and deeper then the one with highflow cats.

So its up to you if you want off road or not. But keep in mind it will fail emissions and the visual test aswell as there wont be cats. You can go with an X-pipe which is shaped like an X instead of the stock setup which shaped like an H like it sounds.

The X pipe will give a higher pitched sound which sounds raspy to me and i dont like it. It does give more top end power with less torque then the H. While the Hpipe will give lots of low end torque and have a deep old school muscle car sound. The power difference is minimal between the two like 1-3hp so choose on sound be happy.