Let me tell you this, since this is your first BMW. Putting in a low quality batt that doesn't match oem specs can leave you in a world of hurt when electronic modules start failing and the cars systems cannot operate properly. Batteries are a BIG DEAL on bmw's, just keep that in mind. Are there aftermarket batteries that work well of course! but you have to do your research don't just grab an H8 off the shelf and think it's gonna be a headache free process.