I would buy one, but...
I just bought an intermediate pipe and trying to determine the choke points in the exhaust. The donut's inner diameter is something like 2.39".
The pipe on which it sits is even smaller inner diameter.
This has to go, but some kind of flexible section would have to be added.
The Tomioka downpipe has a shape that works, something like that in a 3", with a high flow converter and maybe a resonator too, like the HKS single scroll (below) and like the V9 OEM would work for me.