Your dumb fuel mixture question of the day
 

Does the 2017-18 3 models adjust for the amount of oxygen being fed to the engine? If you go up and down in altitude, isn't it adjusting the fuel injectors? If you found a way to cram in more air, would it adjust the fuel ratio to not be lean?

Having said that, I read someone recommending against boost in the Skyactive engines, because of the higher compression they already have. Is that really a bad idea? If you just even fed a high-flow air cleaner with a scoop that mimicked that old Ram Air system on the Firebird, would that be a problem?

Yes, any modern car will adjust the air-fuel ratio with altitude.

As for the turbocharger, you might have bought the wrong car if you wanna go drag racing. There is a turbo kit in development, but I have a feeling it's gonna be expensive and they're only shooting for 300hp or so.

Turbo Kit in Development for 2014+ Mazda 3 & 2013+ Mazda 6 | CorkSport Mazda Performance Blog