Wastegate valves on diesel engines

I think what you're expressing, just getting soot getting the boat on plane is somewhat normal if you're giving it throttle somewhat fast, what happens if you slowly bring the throttles up to cruise? If you're not exhibiting smoking at idle to slow speeds and no visible smoke at cruise, then your motors are probably fine and would leave them alone.

No need to do either, just look at your inlet air pressure readout and usually it should be under -5, if it's high like -7 or more, you have a restriction somewhere. But I don't think that's the case. But if you have a camera phone, take a picture of each screen when running WOT, easy to go back to. Was the bottom and propellors clean (I'd imagine so since the boat was out of the water getting painted.) Some soot is always going to be normal and might be more pronounced if you have a tail wind, or if you have the enclosure closed on the flybridge causing a station wagon effect (even though Cabo's don't usually exhibit this much). It might just be the way it is.

Everything leads me to believe that everything is normal. If you were getting a station wagon effect and had everything closed on the bridge, it probably made it soot up more. Do you normally have some airflow going through the bridge from the front? I honestly feel everythings normal, but aren't there. It's also possible that your shiny new paint job is showing the soot a lot more. But, it could be injectors or something like that.

Yes, increasing boost will increase acceleration from around 1400 rpms to WOT, should also make more HP. Now, you'll make more HP with more boost so you should turn more RPM's at WOT. If you cruise the boat via load factor than your cruise speed should be higher. If you cruise the boat at a certain RPM point, say 1900 rpm's than your speed at the same rpm's will be the same since you're turning the propellors the same speed as before at a given rpm (unless you add pitch). More boost will also create more heat in the cooling system, but if you're running normal operating temps it shouldn't create an issue.

technically yes, if you're making more power, everything else being equal, your load factor across the rpm range (while in boost) should drop. But given that you're showing 80% at 1800rpms, and 75% at 1950 rpms, 1950 rpms would be a better rpm to run your vessel at as the information tells me that the motor's working harder at 1800rpm.

I'll have to look at the set of MAN 1100's I run, next time I run it. I seem to remember they run between 26-28 psi boost at 80% load depending on what RPM 80% load is. In that boat rpms at 80% load vary 125 rpms between full fuel and 1/4 tank.....Full fuel is around 2080 rpms, light around 2200rpms, boat does achieve 2360rpms WOT at full weight. If they make 28lbs at cruise I'd bet they make 32 at WOT, seems to me they did at WOT but cannot be certain.

I'd run it at 1950 rpms or whatever where it's at 75% load versus 1850rpms and 80% load.