Optimax 200 with 225 ECM?

[Bjorn]

I have a 2002 model Optimax 200 and just wonder if changing to a 225 hp ECM will give me a nice 25 hp increase? It seems to me that otherwise the 200 and 225 are completely similar.

[sosmerc]

If you have carefully checked all the part number differences and similarities, then I suspect the ECM may be the difference. But on the other Optimax models such as a 135 to a 150, the size of the air intake opening is different.
The 225 might require more air to add to the extra fuel and or timing that the 225 ECM probably provides. So you really need to do your homework to be sure......and at the very least, be sure the 225 ECM you use is from the same year and serial range as your 200. Merc has made numerous subtle changes that complicates the process of parts switching on these engines (it's not as easy as say switching things around on a 2.4 or 2.5 standard carb or efi model).

[Bjorn]

Thank`s for your input sosmerc.