I know most people buy the prochamber for its sound....but does it make the car pull any harder? Also Im running 2 chamber flows right now, would the sound be noticeable?

 

The main reason for the pro chamber is to get rid of the many cats the car has restricting the exhaust and the chamber helps the exhaust see both outlets and run out faster with less restriction, same as most x pipes, a little better than the h pipe. It also allows you to go from 2 " diameter to 2- 1/2 inch, again, less restriction, any catless pipe will show a nice rwhp gain, though yours would run into a chambered muffler it would still be louder, no cats!

 

And would the Stang remain street legal as far as emissions checking?