Ok, coming up against a brick wall here.
Pimax 8K, PiTool 188.8.131.52
I can change the 4096 setting to 8192 ok. Now here is the catch - if I want to run PiTool Render 1.25, SteamVR Vid and App 100% - I am coming up against the render limit of 8192 when I am running Wide FOV with FFR Aggressive PiTool settings.
If I try changing the value to 9996 as is the largest pixel count on the render settings dialed in, I get normal scale on my right eye and my left eye the image scaling goes double or so. If I change the value to anything above 8192, I get the same effect making any 100% SteamVR render and PiTool render setting above 1 with Wide FOV un-achievable.
Now, that being said, hitting the 8192 limit is pretty nice and for some reason I get better fps in Il2 with it than say 7068 x 3600 which is SteamVR Vid 50% of PiTool 1.25 with SteamVR App at 100%.
Wierd but a heads up and artificial limits should not be imposed by SteamVR. I am sure that within a half year or so, we will be able to drive such resolutions in VR.