I picked up an expansion chamber for my DT400B for only $94. The seller said there is something loose rattling inside the pipe and he assumed it was a baffle plate that had come loose. Expansion chambers are hard to find for the DT400B so I gambled and bought it. Plus expansion chambers don’t have baffle plates. It ended up being a mud wasp nest that came unglued inside the pipe. I was able to crumble it up with a plumbers snake and dump the dried mud out the end of the pipe.

This is an odd pipe in the fact that it has the proper mounting points under the seat, but it dumps outside the frame just ahead of the rear shock instead of being fitted to exit behind the rear shock like the Bassani pipes I have on my 360As.

I believe someone started with the Bassani pipe and they cut the back portion off and welded on the back portion of a Hooker pipe. The exit end (stinger) is the exact same design as my CT Hooker pipe. It’s unique but it sure woke up this 400 and of course I love the sound.

imgur.com/a/g58QzyQ