Berk HFC Failure?! Need opinions.

km1346

Hello everyone.. So recently I've been hearing a faint hissing noise from my HFC/Headers area WHILE I am accelerating. It has become much louder in the last few days..

I know it is common to hear this when the RPMs are coming down.. but you can hear it hiss when the car is in idle and when you rev it/drive on it between 1-2.5k RPMS. I bought my Berk HFCs used a while back from a local Z owner but they were pitch black when I got them (very used) I have about 8-10k miles on them myself and have never heard this.. Do you guys think the HFCs have failed?
My idle is fine (700-850RPMS)

I already took it to Nissan and the Tech told me that he checked all the bolts and gaskets from my HFC all the way back down to the exhaust and has not found any leaks and believes it may be close to the headers but he cannot find out until he takes it all apart. Below is a link to a video where you can hear me revving up..

Link:
http://vid1286.photobucket.com/album...psezhhdh8c.mp4

If that doesn't work click on this below




Anyone have any idea what this is?
Should I replace back to stock cats and see if this fixes it?

The help is greatly appreciated.

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