The sound is perfect for me. I am pleased. As for performance changes there were none changes with Air Intake or Exhaust and I did G-Timer test to confirm that. The computer basically de-tunes the car so expect gains unless you combine your mods with a tune change.
When I added Ken's Lund Racing tune after intake and exhaust, my 0 - 60 time dropped 1.2 seconds. That's impressive.