Just as the title says, how's this going to affect my setup? I have a stock deck and I am planning on, either replacing the stock speakers only. Or using a JL CleanSweep, my Alpine V12 MRD-F752 amp with some nice components.

Two days ago, my front left and right rear speaker blew. So, I'm shopping for replacements and all the 4x6s I see are 4ohm speakers.

 

Hey, what you will be doing is going to cause great affect to the circuit, changing out 8ohms to 4ohm is droping the overal resitance, or load the circuit sees. So this will create greater currrent draw, heating up the transitors and resistors on the board of the circuit. (radio or amplifier). I would replace the headunit all together, and run the 4ohmn speakers. Its not just about hooking speakers up either, the more speakers parallel or series, will effect the overal ohm load to that side or channel. You need to measure ohm at the terminal of the output for your net ohms on that channel. (at the radio)

Great question!