This was in July 2002 on Lake Michigan. The temperature was probably in the high 70's, normal humidity, and I'm not sure about the elevation. Maybe 500 feet above sea level?

The reason for the reference to the tabs being level is because I tend to trim and tab the boat conservatively (safely!)

I should also mention that I'm running two sets of mufflers which individually shouldn't knock the horsepower down that much, but in tandem, I'm sure there's some affect.

I'm running CMI elbow top exhaust with their internal baffle muffling system. It's a kind of honeycomb assortment of internal baffles. Then on the exhaust tips, I have external Corsa mufflers as well.

how many RPMs

Approximately 5300 on a Faria tach. Hard to read accurately when going full out.