I have a 2011 150 Speedster 255HP
There is a yellow plug that is attached to the top plastic cowling, which is the tube to the throttle body for fogging.
I hold the throttle at the throttle body wide open and turn over with fogging oil attached to the tube. It is in drown mode this way so no start. I do that for 20 seconds and that's it. I is pretty much the last thing I do.
I also then pull the intake at the TB and attach the hose to my shop vacuum. I run that for a minute to pull any condensation out of the intercooler.
Before all of this I use a pump to flush with antifreeze.
Absolute last step is I blow out with presussureized air, put stabilizer and send it to be shrink wrapped.
Again, here we get -20s Celcius in the winter.
Some will say I am wasting time running antifreeze, to just blow it out but the year I bought the boat it had a leaking Intercooler.
I can easily see how just a little water left in one of the tubes will cost you the IC..