I see common sense evades some still.
Someone almost hit the head on the nail.
What you got here is your replacement speaker is 4 Ohms and you have the factory tweeter wired in also (its a 4 Ohm). So you have the headunit bridged. You cant do that, period.
Your speaker will operate no different in phase or out of phase outside of the phase shift. Anyone who says anything different obviously has no place answering technical questions.
BTW see you on the Alero board!
There are a lot of smart people ont hat board. however there are even mroe idiots that shouldnt be answering questions.