Just installed it yesterday....well let me be honest and say my opinion about this product!
first of all the instructions and install went smooth.
CEL: NO cel on my 05 track (for those whom wondering if its gonna throw it on)
sound: sounds like stock under 3k rpm, over 3k it starts screaming and I like it!
performance: dont know what to say, definitely not what I expected. again under 3k rpm just like stock, over 3k there is slightly more power, when I say *slightly* I mean it. I think the power comes in the mid and top end range.

either I'm satisfied or not. well, paid 500 bucks for a good sounding and minimal performance gains. i'm gonna leave it just like that.

just my review and nothing more than that.

 

Congrats and welcome to the club.

 

Low end power is always easier to "feel" than mid-top end power. You almost need a dyno or some other method of realizing the power gains. You can be assured that you put some of the nicest HF cats available for the 350Z on your car made by some guys that will back their stuff up.