The more I look at the pic, the more that metal between the resonators looks like a brace and not a shield. I think the part rattling is the outer covering of the Y-pipe. I zoomed in on this pic and you can see that there is some type of shield over the bare pipe, specifically the area after the flex joint (moving toward the "joint" of the "Y" in the Y-pipe):



That's probably why when one gets an A/M exhaust, and gets rid of the Y-pipe, that any rattling experienced goes away after that.

Yup, there does seem to be a shield around the Y-pipes. How long did it take for the rattling noise to appear on your car?

I cut off my y it's still there. They come from the Flex joints, you need to get rid of those and put some high quality flex joints in. That's what I might do next.

Do the Aftermarket Exhausts change the flex joints? or are the OEM ones used?

AM exhaust such as FI do replace the flex joints with solid piping and there are NO rattles whatsoever, but the magnaflow incorporates the flex joints to stay close to OEM but has their own joints which im guessing are better quality!

You ever isolate what was causing the rattle in the flex joint?

1. Brand? (Berk or FI or other) - BERK
2. CEL or none? - yes, after they been on for year and half
3. Approximate length of time since you've had them installed? two years
4. Stock exhaust or A/M exhaust? stock
5. Labor charge you paid (so I can get a rough idea, I know how much it costs here)? 150
6. Where did you purchase the HFC from and when? from berk in 07
7. Amount you paid? 475 ish

Hmm, only 1 CEL so far. Wonder why Lucky's the only one so far?

I've tried several times, but i don't really have a lift so it wasnt' so scientific. the theories are that as the exhaust gas pass through it, because it only happens when the Rpms drop and only at a certain point around 2k rpm we were guessing that the pressure is causing air to be sucked in through the flex pipe causing the sound. SOme people were like it's the pipe moving but i had it on a lift last time and the pipe does not flex. It's also possible that it's just the noise that comes as the air flows through the HFCs and the flex joints are so thin and such that the noise travels out through there.

does everyone who installed HFCs have this rattling noise? because so far I haven't heard anything from my HFCs apart from good things

i got a CEL. stuffed them with SS wool and that was the end of that. been about 1,000 miles now CEL free. the HFC can be a headache CEL wise but i think my troubles are over now with the SS wool. many over on my350z.com have had success with the SS wool. if it ever comes back, i'll have to do the new CEL fix that i saw with the 2 non foulers and drilling one out or whatever. surely the SS wool PLUS the 2 non foulers will keep the light off.

^ how long did it take for your CEL light to come on?

That's my lovely pipe organ.
If you guys want any specific close-ups, just let me know.
I'm happy to post more pics if needed.

Ya, I couldn't remember who's pic that was, but I have it saved for reference

Closer pic...