We're the internet experts, don't trust us.
Peak stock boost* on an Evo VIII is in the high teens, Tyler.
(Peak boost on a FiST is 22ish, FWIW).
Individuals cars vary enough that it's definitely worth taking the specific car in question to a reputable tuner and doing some data-logged dyno work.
*from the factory. As opposed to
max boost, which would be what you
could run in a given car.