I sent a note to SGH innovations. In a youtube video they have a Tesla Gen2 iBooster hooked up to a factory pedal and have a pressure gauge on it. In the video it only shows it going up to 300psi or so, which made me a little nervous.
This morning I sent an email, and got a reply that it can get to 100 bar (1450psi) on the test buck on a factory 26mm master cylinder. The gauge in the video only goes to 100 bar, so not sure if there's more capability, but it at least provides a number for some calcs with the stock master.
So here's a screenshot of the tweaked Billavista brake calc using that info. I adjusted the boost multiplier to hit master cylinder pressure of 1450psi using a 4:1 pedal (not sure if Tesla is same as Accord, but I'd guess so) and the 26mm master cylinder.
Between seeing a local guy make 2004 F250 rear caliper brackets for a 14-bolt and
HYDRODYNAMIC fitting them to the bigger F550 dana 60, it made me look at how'd it calc out on my buggy. My biggest struggle is that my stock 05 Super Duty D60 calipers are huge and make for a PITA hydraulic ratio. The 2004 SD rear calipers get the ratio better, and based on the calc I should see an easy 10% improvent in brake torque over my manual setup and not need the crazy throw from a 9:1 pedal.
One thing about not knowing if 1450psi is the max with stock master, is that it doesn't help to know if there's more if a bigger master were installed. All else being equal, a 1.125 master would produce 1200psi, 1.25" @ 978, 1.313 @ 887psi. But if the multiplier is larger, then obviously you would have more headroom.