I'd suspect something in the carbies making the noise but without fiddling around with it and a piece of diagnostic garden hose it's hard to guess. Having a dyno so you could run it up and then get around it with the hose to pin point the source would be very useful. I'm sure someone on this forum has come across it before...

My thinking is that there might be some kind of restriction or resonance going on there or something's not quite tight. COuld even be a piece of gasket partially obscuring a passage in the carb making the noise at a particular speed. You'll figure it out I'm sure.

Hmmm ... it does not seem to lose power when it makes the noise, and will rev higher at which point the noise ceases.

I'm sure it's not, but it sounds very similar to valve bounce.

burnt squirrel or Opossum skeleton tickling the muffler?

pressure reversion?

Is it that higher pitched squeaky sound you're talking about? (The snarl.) Other than that it sounds really nice. Sounds a bit like a funny bearing but not quite. Not sure what that could be.

Video is dark, but I'm revving it to about 6500. As it sweeps past 6 it makes the sound. It is more pronounced when actually driving the ute, in the video it is just sitting in the garage.

10 second audio

Can you upload a vid? I want to hear it now..... I do love the sound of throaty ITBs without silencing. The air cleaners keep some of the noise in. I bet if you put some hose inside the air cleaner and listened to the other end you'd hear the snarl.

I don't know about guns. I haven't seen one in many years.

It snarls on full throttle at high RPM. Before backing off. Not sure why, it doesn't do that with the air filters on.

cannon muffler illegal but a cannon of a shotgun is not? :)