1) I think you are misunderstanding ohms. Ohms is resistance. So your 2ohm speakers are providing less resistance than typical 4 ohm speakers. Therefore they are getting MORE power than 4 ohm speakers would.
2) Your aftermarket headunit is not 52w x4 Your reading the MAX wattage when you need to be reading the RMS wattage. Its actually probably between 20-30watts into 4 ohms. I can almost guarantee you that it is not rated for a 2 ohm load. On top of that you said you replaced your 2 speakers with 4? Are these woofer/tweeter plate speakers rated at 2 ohms? or two 2ohm speakers that you wired up? two 2ohm speakers can be wired at either 4ohm (perfect) or 1ohm (BAD!!).
So as said before, they are either blown, or its your ohm loads messing things up.
