I got a stock k20a3 turbo making about 275HP at 15psi of boost. Issues that arose was stock clutch and stock fuel system limiting the Potential Horsepower that it could make. Changed to stage 4 clutch and now have a return fuel set up with regulator to run E85 with injectors and fuel pump. The HP gains per pound of boost is about 7.6, my set up is rated for about 300-400 horses before I run into turbo problems, but for the build that’s plenty. Raising boost to about 25psi and adding E85 which is automatically a 50HP gain in most cases. The car would make about 400 theoretically. Or use 5psi less and be at 20psi and be about 360HP. Sounds realistic to me given what the car has achieved already, and having cooling properties from running E85 let’s hope the engine can last.