Originally Posted by portishead
The only thing blocking me from buying and installing them is the 2-Ohm rating factor. Will this potentially overheat and fry the factory head unit?
Any amplifier has a wattage rating. To get that maximum rating transferred to the speaker, the speaker impedance must equal the amplifiers internal impedance. If the impedance of the speakers don't match, the power ( meaning heat) dissipated inside the amplifier will be greater than designed for, for any given volume level.
What this means (for example) is if the volume control was set to 50%, the volume at the speakers would be louder if the impedances match. It also means that the amplifier would run cooler if the imdedances match.
Since the amplifier will be running hotter than normal, it means the amplifier might reach it's maximum safe temperature at 80% volume, rather than 100% volume. Most modern amplifiers have thermal protection, so they will shutdown when they get too hot to avoid permanent damage. But as I said earlier, the volume of the speakers will be less than normal for any given setting, so the maximum volume out of the speakers might sound like only 70% of what it would be with the correct impedances.
Your idea to put 2 speakers in series to obtain the proper impedance would work. You just replace each single 4 ohm speaker with two 2 ohm speakers in series. It will look like a single speaker as far as the amplifier knows. I'm just not sure where you will get the space to add the extra speakers.