How much is too much?

Our 2008 Supra 22’ V drive (with an Indmar 325 MPI) was running rich. It had a strong odor to it when surfing or when in reverse. We bought a $15 fuel injector pressure kit from Harbor freight and measured the fuel pressure on the fuel rail. The gauge measured 100 psi. Larry, at Indmar, Said that maximum reading should be no more than 60 PSI. He recommended this fuel pressure regulator. It was a simple one bolt install. It corrected the problem. The boat now runs great. I’m not sure why it cost so much, given the automotive industry’s prices, but I am happy that it worked out well.