As far as the owner knows, the engine is all stock with about 90k miles on it. The car does also have an EWG. I don't believe the injectors are really maxed out, but rather the fuel pump is dropping pressure on the top end. I recommended he upgrade the pump or direct wire it.
Like we said, this one shocked us all here with the power it made and how easily it made it. Either its a freak, or there's something about the setup he's not telling us or doesn't know about.