There's no need to go to a 16" tire. Best bet is a 15" and save some money. Just make sure the overall diameter is roughly the same, but I'd say you know this already.
There's a rumour that a dealership in Ottawa I think, has a package deal for 185/65/14's for all protege's. The dealer here has some on the way anyhow, I'm going up end of this week to see if they fit as well.....got my doubts though.
Are the brakes any larger on the MP3 then the ES 2.0? How about bigger then the SE? because the SE has 14's.