I just figured out that the K & N air filter I had in my 6S DOES fit in my MS6. I thought I was going to have to sell it on E-bay or here, but nope -- fits perfectly! I assumed the 2.3 would have a different filter. Silly me.

interesting, i too would think the n/a and f/i would have different filters too, shows what I know.

One less parts bin in the factory. I'm sure it saves them good money to do it that way.

That makes sense. Now I have to get a sticker for the airbox so the mechanics don't swap it out during maintenance.

I wouldn't be surprised if the filters are the same size in all the mazda models. That way they only gotta stock one filter.