Just installed the 5Zigen Fireball exhaust. Cost me $250 total and I love the sound. To my surprise, this straight pipe design is not at all noisy or loud... in fact, the sound produced closely resembles a Turbo Car muffler. As for performance, I'm not quite sure how much power increase 5Zigen claims to have, but it definitely makes the car sounds like a sports sedan. I can actually hear my car now when I accelerate. Maybe its just psychological, but at high speeds, the car feels smoother. The noise level at 85mph + is about the same as stock.