The Catalina 27 is the perfect example of whence I speak. The boat calls for a minimum of 15hp. But, using the Yamster HT9.9 you can make up for being grossly underpowered. It's a good solution. This is probably a good time to add that I know of no outboard that was designed from the bottom up as an auxilary. All brands that offer a gear reduction model took a standard model outboard and then altered it in some way. The HT 9.9 is a good example of a highly modified model that provides a single purpose use. For anything other than pushing a heavy load it is useless. But if that's all its going to be used for it is a solid performer. The Tohatsu 6UL is at the other end of the spectrum offering a minimum alteration of a standard 6 hp with only two modifications: An extra long shaft and a battery charging system.
The "Pig Prop" was in stock this morning with3 being available. We are in Tampa so delivery is next business day. I've never had anyone ask what the pressure was at any RPM before
I'll check and see what specs they have available or you could call Tohatsu direct at 972-323-6003 and have one of their tech support guys tell you anything you want to know.
That 6 sounds like a fuel or ignition issue. More likely a fuel issue. Could be as simple as a piece of trash floating around in the carb that sometimes blocks a jet. Fuel related problems are about 90% of all service failures on engines in the marine world. Regardless, the engine has a real problem and you should run it by a service center. Let me know where you are and I will direct you to the best of the dealers in your area.