The better fix will be a nice little single turbo setup.
My rattle seems to be getting worse.
And a rotating seat? That's rediculous. You'd think that this is the first time this kind of thing has been attempted. In all the miles driven on a stock turbo setup RX-7 of ANY generation (in particular the 3rd gens), I've never heard of any WG rattle. And the valve face was certainly not any rotatating type.