As for the 460, I didn't build it, but in going through the receipts there was nothing besides a cam and cleaned up heads that would indicate a large HP change over stock. If I wanted to get optimistic, I suppose I could say the boat made 400-425, but you have to remember that the printed impeller selection guides represent an average. So if you take in to account that fact, along with an un-dyno'd engine, I have little reason to doubt the AA or the tach. I've driven plenty of Spectras with jets, and I can tell you it definitely wasn't an A impeller based upon plane times and lower RPM performance. One possibility is that at WOT, and trying to trim for top speed (relative term ) the pump was seeing some cavitation. The boat was used primarily on Havi and never really saw "smooth" water.
Tach was accurate to the digital RPM on my timing light, so good enough for government work.
When you look at data across multiple boats, you can only gauge trends, not absolute values as there are multiple variables that will affect one or more of the reported data points.
hope that helps
Possibly my fav jet on the planet
