Just had mine installed this morning. First impression is that it's well-built.

It really growls during acceleration, but drops down to a purr when cruising. Can't say that I notice anything different power-wise 'cause the noise grabs my attention more than anything else. It's quite a bit louder than I was hoping for, but if my gas mileage improves as advertised, then I'll be more than happy to live with the increased noise. Still hoping it'll mellow out with time though.