After doing a little looking around and reading, I've figured out that my problem is a result of running too lean. It appears that since I've had the intake and exhaust installed, the A/F mixture is allowing more air than fuel. I haven't done a dyno to get the readings but judging from the effects and the noise I'm hearing, it seems reasonable. Because of this, I'm going to send out the ECU to Technosquare so the timing and A/F ratio can be tweaked.

 

Highly doubtful it's a result of any bolt-on mods. A stock VQ35 fuel system is big enough to handle bolt-on mods.

The 350Z is extremely sensitve to knock, it just runs really high timing from the factory and aside from getting a new ECU, there isn't much you can do except run the highest octane you can find. It's easiest to hear when the engine is under load - very low RPMS with light, constant throttle inputs, going up hills, towing (not with a Z, just an example) and you can even get A/T trans. cars to knock if you powerbrake it near the stall RPM. Knock sensors simply react to the knocking and pull timing out, not prevent it from ever happening. Chances are if you hear it, the ECU will start pulling timing out and the car will get slower. This is the main reason you'll get inconsistent dyno readings and/or 1/4 mile times. If you don't believe me, borrow a Consult 2, dyno your car or just drive around for that matter and watch how much timing the ECU pulls out when you step in the throttle.

 

hi
the knock is essentially part of any engine built since about 1985. The knock sensor is constructed and located to detect the knock and the computer quickly retards the spark timing. The computer is also working to advance the timing to realize as much power development as possible in each stroke. This is a delicate balance of air, temperature, engine temperature, fuel air mixture, octane rating (the real one, not the one printed on the side of the pump). If you have some spare cash, find a gas station with real fuel (like 100 octane) and put in about a half tank (this will be close to 30 dollars for 6-7 gallons- color will be kind of purple). Then, drive around to get the engine hot, and to mix the gas. Then, try full throttle start- if you do not hear the knock, then you can conclude that the octane is the issue, if the knock is still there, it is indicating that the timing is perhaps a bit too far advanced (*although I cannot figure how the computer would allow this condition to occur). You can retard or advance the base timing, but it is a bit tricky, and you need to have a timing light, and a friend to help adjust.
Good luck.