Nice Matt, would be nice to know if he's still a bit nostalgic or not ! Where are you working btw ?
I had a look at the pictures I have from the turbo I talked about earlier, and unfortunately I only took pictures of the housing and not the restrictor (which was modded too) but you'll get the idea behind it.
So the principle is that air can bypass the restrictor (as you can imagine) and go through the machining work that was done to the housing AND the restrictor. So the engine gets more air. It was discovered of course but maybe that trick is new to people here !