I have th S200 430HP. Trying to find info myself. From what I have read and the charts I have seen 11/19 would be for the 155NAs and i would go 14/19 for my boat. Really curious how this goes for you. I bought the wrong impeller tool, the WR011 for 4TEC NA not SCIC, if you do change yours, I will glady mail my tool to you for a report back!
TIA Ned