Best Cruise RPM and Manifold Pressure

I have found my RANS S-12 with the 912UL cruises best at 5150 rpm. It settles in there pretty good and yields about 85mph airspeed. If I bump it up to 5500 rpm (like a lot of guys say you have to run the engine) I'm flying at 95mph which is 5mph short of VNE!

5150 (which also happens to be the recently deceased Eddie Van Halen's favorite number) yields me about a 3.85 gallon per hour burn and gives me the best overall performance for cruise.

NOTE: The discussion above is for solo flight. I find when I have a passenger, 5150 only gets about 80mph and burns a little more gas...

My instructor told me that he doesn't like running his engine above 5000 rpm for more than a few minutes even though max continuous is much higher but his engine is also past TBO so maybe the "best" engine rpm is different if the engine is older? I don't know.