1989 Evinrude 25hp vs. 35 hp.

[rrichards007]

I'm looking at buying a 1989 Evinrude 25hp. I really want a 35hp, but I found this 25hp for sale locally. I know there were minor differences in the engines back in the 80's. I am looking at the parts list on boats.net and cant find anything different. Part #'s for the carb, intake, exhaust tube, etc. are the same on the 25hp and 35 hp. There is a midsection listing for 20hp & 25hp only and 30hp and 35hp only, but again I cant find a different part # in those areas.
Does anyone know what I would have to change on the 25 hp to get 35 hp out of it?

Thanks.

[boats.net]

No never tried it not sure what difference is.