i dont think you'll get 300hp at 1 bar of boost.

a t3 on a cosworth YB as an example will still be reliable at 2 bar of boost (30 psi peak). If the turbo has had a refresh then i dont see it being an issue at 2 bar. but it depends on the condition of the turbo.

when you start running 34psi spikes you'll run into problems.
i ran my t3 at 28 psi and had no problems at all