HondaCutter

Ok, I searched and read almost every single thread ( archived and recent ) and noticed that no one received any real closure on the situation. Let me tell you mine.
I have a jdm b16 with DC 4-1 header, apex WS exhaust. All gaskets are new, I've been working on this problem for a while and in the process replaced all gaskets, including the donut gasket with a new OEM donut gasket.

when I did the swap, I bought a new cat from autozone. For those that do not know what the cat from autozone looks like, it doesn't look like the oem cat.

-it has 2 inch piping with a big bubble in the middle which is where the cat stuff is contained.

-it's a 2 peice cat, the pipe with the flange that connects to the exhaust goes inside the other part of the pipe and you clamp it with a supplied U clamp.

Right away, I was experiencing a rattle which I assumed was an exhaust leak due to the U clamp no creating a good seal. So, I had a muffler shop weld the 2 pipes so I wouldn't have to use the U clamp. I still had the rattle, so I had the muffler shop make me a test pipe, using the flanges from the cat. I still had the rattle. My friend had an extra OEM cat, it was gutted, but I still gave it a shot ( thinking that maybe the welds were bad or something). But with the gutted OEM cat, the rattle got LOUDER. So I put the test pipe back on and now the rattle is still there but not as loud.

I've removed heatsheilds by the cat, replaced the spring bolts with solid bolts. Still there.

But while I was reading through the posts that I found in the search someone mentioned that if you have a test pipe, it's going to rattle regardless of what you do.

Is this true, do all testpipes rattle? If so I'd be satisfied knowing that it's not an exhaust leak, just the testpipe.

Any help is greatly appreciated... THANKS!!!