I have a 3inch catback exhaust, aftermarket y pipe, stock cats, i have this noise that almost sounds like a burrower bee buzzing noise every time i accelerate/ am going a constant speed. I have looked everywhere on here and posted videos on facebook groups and no one can figure it out, i work at a nissan dealership and the mechanics cant even figure it out. I replaced both gaskets were the cats join the y pipe and it is still making the noise, Do any of you have a similar issue? Like i said it sounds like a buzzing noise almost like a powered razor (id post a video but it wont let me)

 

is it a resonated cat back? have you checked the head shields to see if they are vibrating

 

It is resonated, and i took all the heat sheilds off when i installed the y pipe so there arent any heat sheilds on the car so thats why im getting frustrated

 

it is possible that the material in the resonator could be busted loose

 

Should i just have a muffler/exhaust shop check it out then?

 

take resonated part down.... hit it with palm of hand, if it is loose you will hear it

 

Could stick your stock system back on and see if the noise goes away if you still have it. It's odd if a mechanic looked it over and couldn't figure it out unless they did a half assed 5 minute looks good to me bro kinda diagnostic. How are the heat shields on your exhaust manifolds and catalytic converters?

 

Bump. I'm having the same issue except it's mainly when I'm DEcelerating and it's pretty unique to about 1800-2500 rpm. I do have resonated test pipes - Megan. I didn't think there was anything in the resonators. I thought they were just an empty cavity. Are you sure about ^this?
I crawled under it for a long time today and took the heat shield off of the y-pipe. No change. Listening very carefully under it, the noise is almost certainly coming from the flex pipe on the driver's side. It sound like there's a freaking marble rattling in there! But, you can't hear anything from tapping/banging on it without the car running.
If this resonator "material" is true, I bet a chunk came off and worked is way downstream to get stuck in the flex pipe.
Sound reasonable? Any other suggestions?

 

If they didn't have any resonator material in them I think they would leave the word resonated out of the name. I know when i had a test pipe on my old car it wasnt called resonated because it was a straight piece of 3 inch exexhaust pipe.

But it sounds like you might have pinpointed your problem so you should probably remove that side of you y pipe and see if a piece of megan racing quality comes out of it.