Hi i have a version 6 sti which has been tuned to 17 psi on a stock vf28 turbo with a autronics ecu tuned to 241hp at the wheels with a 3 inch stainless exhaust with a front mount, i am thinking of upgrading to a vf34 if i do will i need to retune my car again? seeing as the vf28 and vf34 are very similar?

You will definitely need a retune

VF 28 & VF 34 are nothing a like (apart from both being ball bearing turbos)

The VF34 pulls harder everywhere over the VF28......Retune or DOk Dok....

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