The sound deadning material is alot of weight. Rip it out

 

pull the engine and put in a b18, then strip the factory exhaust and make sure to get a 6-8 inch tip for the 1.5 inch straight pipe. Then your car will be FAST AND FURIOUS WITH THE WEIGHT REDUCTION

 

did u say b18??? lol yah thats just what u need for your mustang, serious thou dont rip out all that ****, trust me i know.I use to have an integra that i did all that rice boy **** to and at best dropped .3 sec off my 1/4 mile not worth it.The only thing that made real horsepower for that car was 75 shot of nos .You wanna go fast make more horsepower!!!When you have made all the horsepower your car can take.Then start thinking about weight reduction,just my 2 cents.