I replaced my WRX battery with an Optima red top a few years ago. I had a ground cable corrosion problem on the engine block end, and went in for warranty replacement (free is good). The head of service tells me I voided my electrical system warranty. I talked to the dealership manager and told him what I do for a living. After they knew they couldn't bullshit me, it was all covered after that.

Anyway, if you're so worried about a CAI, there are two things you can do. Either don't install a CAI, or swap out the CAI for the stock intake if you need to go in for warranty repair.