Tinny exhaust resonance

[Judge]

I've got a really irritating tinny resonance coming from my exhaust (back of the car, not underneath). It starts at around 2500 rpm WOT and continues all the way to the red line. It's not really noticeable part throttle and does it briefly when revving WOT in neutral as the revs pass through 2500 - 3000 rpm. Initially it sounds like there's an angry rattlesnake in my back box, but at higher revs it almost sounds like there's a circular saw strapped to the back of the car. Here's a link to a short clip of it. https://youtu.be/jDQ4JZ3nyG0

 

My car is a 2008 350Z and current exhaust setup is stock headers, Motordyne ART pipes, Powerflow Y-pipe (leftover from CBE fitted by previous owner), Fujitsubo Legalis R mid section and back box.

 

This all started after installing the ART pipes. I'm assuming they're not what's making the noise, but are a contributing factor because of the increased exhaust gas flow and decreased muffling compared to stock cats.

 

I don't think it's the Fujitsubo (even though the tailpipes are a bit tinny sounding if you flick them) because the previous Powerflow mid section and back box made the same noise. And I don't think it's the rear heat shield as they tend to produce a lower pitched buzz (I had a cat heat shield issue when I installed the ART pipes so am assuming the noise would be similar).

 

As the headers are stock, that only leaves the Powerflow Y-pipe. Their current Y-pipe has been redesigned slightly, but the one on my car is similar to the Scorpion. There's a slight bore mismatch as the ART pipes outlets are 2.5” ID and the Y-pipe inlets are slightly less than that (2.5” OD, haven't been able to measure the ID). There's also a mismatch between the Y-pipe outlet (2.5" OD) and the Fujitsubo inlet (3" ID) which might not be helping the harmonics.

 

So would replacing the Powerflow Y-pipe with a better designed Y-pipe (that also matches the bore of the ART pipes and mid section) solve the problem? Or am I barking up the wrong tree?!

 

Thanks.

Edited February 24, 2019 by Judge