How to determine speaker polarity?

You old farts..... it took the young guy still in diapers to catch on. You guys are going senile. To check the speaker polarity with that battery, both terminals on the battery must be attached to the speaker........wow, low planes......just got buzzed by the Snowchickens.....Expecting the F18, F16, F117, E6B, KC130, B52, B1B all to arrive today + numerous others.....back on topic. Connect one terminal of the battery to the speaker, breifly touch the other lead on the battery to the speaker, if the cone moves outward with a "pop" then you have the + lead on the battery connected to the + lead of the speaker. If the speaker moves inward, then you have hooked the + lead on the battery to the - lead on the speaker. Reverse and try again. Once you have one speaker, all other speaker terminals will be the same.

PS, I too am long out of diapers but not in any danger of going senile, unlike my counterparts.

I will just leave them the way they are, then. The only problem now, is that I'm a little worried about my factory head unit. The Infinity's that I installed were 2ohm speakers. (what are they thinking) Actually I know they are thinking that I need to trash my factory head unit and use an amp, but not everyone does that. My deck now gets a little hotter than it used to, but really no other issues. I am wise enough to know that 2ohms is merely an estimation of a speakers impedance as it changes radically depending on the frequencies being fed to it.

Should I let this bother me, or just beat the thing til it blows up and put in my Alpine and an amp? :)

I'd go ahead with the amp as you'll probably wish you had anyway. 

The 2ohm speakers, if it presents a problem, can be wired serial from the HU w/o much trouble.  Once you figure which wire's what, do the serial re-wiring in the dash instead of at the speakers.  Of course you'll have lower output now.  Or just leave it how it is now & don't turn it up (yeah, right).

About the pop test with the battery (you can use a regular D-cell if you want, incidently), what you'll want to do is connect the speakers & run the test from the dash where the HU lives.  Then I'd reverse the wires as necessary from there.  I guess it's all the same, but I think that'd be easier & less chance of error.  And yes, you have to connect BOTH battery terminal to the speaker, else no circuit, no speaker movement.