Not sure what to do here, fellas. I responded to a previous thread here:

https://maxima.org/forums/5th-genera...at-shield.html

as I was experiencing a similar symptom/noise.

I still have this issue even after the Walbro and filter install.

The best way to explain it is pre-ignition, the rattle can being shaken noise just before redline and just prior to a shift, and at NO other time! I took a bonafide Nissan tech for a quick drive after he aligned my front end and he was just as perplexed as I. I can stand on the accelerator in park or neutral, bounce the rev limiter indefinitely and the sound will not present itself, it ONLY happens at the top of the rpm range under a load just prior to a shift at WOT.

I'm not sure I understand how it COULD be pre-ignition, as practically everything is new. It's more embarrassing than anything, as I don't think it's anything harmful, it just makes a gawd-aweful noise for a split second when I get on it. I would, however, like for it to be resolved as it certainly is not normal. I hope someone with some detonation/pre-ignition/knock/ping experience will chime in soon, because my car is now ready, and I really want to start stomping on the pedal.

Recap:

2003 SE with 125k mi
2014 VQ with 50k mi
Jatco 4spd Slushbox RE4F04B
New everything else
8k mi on swap
Premium 93 only
Tampa, FL
No codes pending or current
No issues, runs like a bat out of hell
Stock 15 degree timing (was advanced 2 degrees with NDSII. Timing was retarded back 2 degrees to stock but did not remedy the issue)

Anything helps!

Thanks, guys.

Try 1 step colder plugs.

Did you ever get a tune? Lean is going to cause detonation.

No heat shields. It went in just the way you saw it last, completely bare. I don't even have post-cat and Y-pipe shields. I don't think it's a rattle. And I just can't imagine the cause of a lean condition... New pump and filter. The bizarre thing about it, is that it will not present itself under any other condition or RPM value.

Plugs are brand new OEM and good for 120k+, I'll probably never replace them again. I'm 1200mi away from oil change #2 (10kmi on swap). I'll do oil, filter, tranny drain and fill, and new axles. I'll poke around while I'm under there with more focus on parts rattles.

Add: And no, no tune yet. Working on that, among other things.

Good call! I thought about that, but then again plugs are brand new OEM. Something else has to be wrong?