honed out manifold, zzp high flow down pipe, custom exhaust
brought it to dealer exhaust shop replaced all heat sheils replaced all gaskets net bolts
sealents every thing it rattles when i hit 3 grand and above on rpms in any gear but primarally in 1st and 2nd cant figure it out

 

Check your cat. I asked a similar question and everyone suggested it was a downpipe flex pipe or something. I took it to the dealership and it had a blown cat.

The sound usually occured between 1st-2nd at about 3k RPMs. My car however, is completely stock. I got my car back on Saturday after dropping it off on Tuesday this past week.

Also, the sound came from the middle of my car not the back at the tip.

 

I had the same problem that i just figured out. I could here the noise in the middle of my car pretty much as soon as it got warm but espicaly in the lower gears. I took off the whole converter section thinking it was the packing in the cat that blew out, turns out it is a metal sleeve inside the flex pipe section. (think its called a silencer?) All i did was tack weld it in there to keep it from rattling around in there. Problem solved for me.