How much psi or hp can 30mm w/g support?

[JeanDSM]

First of all i was thinking on buying a 38mm tial w/g cus my goals are 350whp. I know that wne i get there then i want 400whp and then 450whp and goes on. I only want to buy parts only wonce at leat most of them. when will a 38mm w/g need to upgrade?

 

[Black94DSM]

The only time you need a large wastegate is when you run a Big CFM flowing turbo, and you try to run low boost. Therefore you are trying to redirect the air that would normally go to your turbine wheel now to the wastegate. If it cant flow the extra air through the wastegate whole, it will revert back to the turbine wheel and create "boost creep".

So the 38mm tial is good for lots of power, as long as you are running big boost and bleading off little amounts of exhaust gas.