I am seeing conflicting information on whether the door speakers in the base 6 speaker system are 2 ohm or 4 ohm. I've read through many of the speaker upgrade threads & see people saying that they are 2 ohm. But I've also watched YouTube videos of speaker upgrades & when they show the backside of the factory speakers they say 4 ohm. Can anyone clarify? I want to upgrade my stock speakers, but I want to match the specs of the factory speakers. Thanks...