STS turbo's run at a lot more than 2-3 psi!!! H3LLO! They are like any turbo...depending on the size of it you can run one at 2-3 psi or as high as 12 psi. They make a bolt on application that is 9 psi strong...They can give a 210 hp v6 mustang 315 horsepower (at the wheels, so more than their GT version) with just 7 psi.