Lots of good stuff here. I'm glad (or maybe sorry???) other people have experienced it / know what I'm talking about.

G35_TX, it's definitely not from the engine cuz I hear it behind me...

Here's a summary of details:
- Only at WOT in 2nd or 3rd gear at about 2500-3000 rpm the rattle comes
- When not in gear and I floor it, i hear no such noise...only the smooth rumble
- I am running kinetix HF cats and topspeed headers but with stock catback
- Getting my HKS Hi Power next week we'll see how it is after I put it on.

I wonder, will a regular car mechanic have a lift that allows someone to go in the car and engage gear while lifted? Like a dyno i guess....it's the only way to tell for sure what the heck is happening. Any other suggestions?

Rick thanks for clarifying the resonated pipes.

 

I have the y-pipe installed on my 99 Max. I never got the "bees-in-a-can" sound. I attribute the lack of the "bees" to my free flow GReddy cat-back.

 

Okay if its behind you then yea its not that. I heard that from below to in front of me with the Bee's in the can. Check the shields..

 

On the early Ypipes they had this problem. The later ones Cattman and a few others fixed the issue with different materials to help insulate the noise.

 

I bought the Stillen unit, supposedly the infamous bees-in-the-can y-pipe. I'll still think that the HF cats or race/test pipes are just letting way more air through than the stock cat-back can handle. The stock cats act as disrupters and the stock cat-back can keep with that.

To look at it another way, a common setup would include a HF intake, plenum spacer, and possibly HF headers in addition to HF cats or test pipes exiting through a stock cat-back. You now have the equivalent of a party favor. Tons of air can go in but it's bottlenecked at the cat-back restricts the out flow and you get a funny noise to boot.

 

The sound the VQ30/35 Maxima's had was what I called a metallic ringing. It sounded like a faint metallic rattle that was emitted from the muffler. My setup at the time was an aftermarket y-pipe, aftermarket midpipe (no resonator, stock had a resonator), and a stock muffler. For whatever reason, it never occured to me that the noise started after installation of aftermarket midpipe. I was convinced the sound couldn't be coming from midpipe because it was just a piece of bent pipe. I figured the stock 8 y/o muffler had finally broken an internal weld and it was rattling. I bought a 4 year newer used muffler and to my surprise, the noise was still there!!! On a whim, I threw the stock midpipe back on the noise was gone. The ringing wasn't caused by the aftermarket y-pipe because numerous Maxima owners with and without Y-pipes reported the same ringing after adding non-resonated midpipes. After talking with a speed shop owner and prior lead tech at ATI Procharger, he was convinced the sound was caused by the V6 layout and firing order of the motor. A similiar sound eminates from modified 3800 series V6 GM vehicles.

The sound that G35_TX is talking about is the infamous "bees in the can" sound as air passes through the unlined flex sections of the Maxima aftermarket y-pipe. This sound was somewhat remedied by adding lined flex sections. Over the course of ownership, I add two different aftermarket y-pipes on my Maxima. One had unlined flex sections and the other had lined ones plus it used heavier and thick guage piping. That y-pipe was significantly quieter, it still had a sweet little hiss that occured above 5000rpms under heavy load. It sounded much like a small turbo hiss.

 

It's just not the gauge, it's the steel content of the piping. I should have made that point previously. You know as well as I that Nissan uses a very heavy and relatively thick low grade stainless steal on their OEM catbacks and mufflers. This dense piping along with the OEM heat shields and insulation batting act as heat insulator and noise suppressor.

 

Mike, I warned you about getting those test pipes...

 

Most of the rattels are gone now that I have the cat-back. I can har a few things bouncing (6k range) but I only have about 8 miles on it now. The car just sounds totally pissed off now. It's louder than I wanted but I can get used to it. It will attract more attention than I was anticipating. It's "temporary" until I go FI next year hehehe.

 

UPDATE: Thanks to everyone for responding to my initial request. Since installing my HKS Hi Power, I no longer get any rattle. I guess it was because of the stock muffler and not the HF cats or kinetix headers. Now, all i get is throaty RUMBLE like you woulnd't believe. Pretty sweet.

 

It's probably not from the muffler but from the single, small diameter stock tubing. This was my contention all along, high flow up to the stock exhaust causes lots of rebounding notes that are typically explained as rattles from shields or busted cats. It should be noted on all info for headers & high flow systems that a high flow cat-back is a requirement.

 

Sorry to dig this up from the grave but has anyone tried to put a reducer on the end of a 3'' y-pipe to eliminate rasp?