haven't heard of too many people putting a mazdaspeed CAI intake in their regular 3, but unless the dealer can pinpoint a problem to an aftermarket part that you put on, you shouldn't have any worries. i actually had to get a new MAF sensor cause some water got in my CAI, but the dealership replaced it for free even though it was technically my fault.
josh, not sure if you were directing the question about the BCC to me, but i do have one on my car. basically it stabilizes the volts you car outputs, and actually gives you a slight power gain and slightly better MPG.
that's from a website that sells it. i think it works pretty well. you can't notice it a WHOLE lot, but i like it.
I'd like to purchase a Sprint Booster, because for us ATX guys, I hear it does wonders when it comes to shifting. Practically no lag anymore between shifts, and a much quicker throttle response. I don't have any personal experience from driving with it, but everyone else who has a ATX MZ3 says it is an amazing product.