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Discovery on STi JDM axleback and perhaps others
Some times ago I fitted the STi JDM axleback, instructions said to replace nuts, gasket, and hangers, but I didn't do it as my car was new.
I was happy with the sound, except an annoying resonance at 3000 rpm.
I asked here, and I was said it was drone, nothing to do, characteristic of the exhaust; it was not drone to me, but a resonance inside the cabin.
Recently I discovered a japanese article: I was right, and I made a great mistake.
I didn't check the part numbers of the additional parts, as I took for granted that they were the stock ones; but the hangers weren't, they were a different part number!
The article said that the cabin resonance frequency of the 86/BRZ is 125 Hz, and the STi steel exhaust (the titanium one don't) needs that specific hangers to avoid the noise. AND THIS WORKS!
If you have resonance, and you want to try risking just few bucks, you have to replace just the 2 rear hangers (the ones toward rear bumper) with 44066AJ010 part number. The front ones has to remain stock.
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