'82 Johnson 9.9 question from a new guy

[quack1]

I have a 1982 Johnson 9.9 on my duck boat.
What parts were changed when converting to a 15hp? Was it simply changing to the 15hp carb, or were there other parts changed too? I would like to bump up the horsepower, if I can find the right used parts, as several local lakes I hunt have removed their 10hp limits in the last few years.
Thanks

[mjrhoads]

Check out Maintaining Johnson/Evinrude 9.9 part 1

"Converting a 9.9 to 15 HP :"

[quack1]

Thank you, lots of very good information there.