sub wiring, 2 10" infinity kappa perfect

OK I have a few options of wiring my new subs. 

I have 2 10" Infinity kappa Perfect subs that have the dual 4-ohm voice coils. 

My alpine amp puts out 80W @ 4 ohms X 2, 160W @ 2 ohms X 2, or 320W @ 4 ohms X 1.

If I wire my subs up seperately and get 160W @ 2 ohms, is it going to do anything different than bridging them together and getting 320W for the both?  Does one set-up work more effecient than the other?

On my last set up I had 2 8-ohm subs wired parallel for the single 4-ohm load to this amp.  It sounded good, but the amp gets hot after about 20 minutes of playing load and goes into protection mode.  The 2 cooling fans on my amp rack help a little, but not much.

Output wise, it will sound the same.  2 ohms stereo is the equivalent of 4 ohms bridged from a mathematical standpoint.  One advantage of bridging is you use less wire. 

If your amp is getting too hot and shutting down, even with the cooling fans in place, I'd suggest testing the impedence.  If that checks out good, and you read strong power at the amp- 12volts (14 running), ground is solidly connected, then turn down the gains down some.  Even if you're not hearing distortion, or your subs aren't bottoming out, this will help.  Back it off a little at a time until it gives you no more issues.

I was thinking the same thing with the subs, but was just curious.  As far as the gain goes, I usually only have it at 1/2 way. 

What do you mean by checking the impedance?  My subs were 8 Ohm wired parellel.  Should be 4 Ohms. 

Anyways, this Alpine amp is about 9 years old.  I guess I could upgrade to a class D amp sometime.  Back then they were mucho $$$, but now they aren't too expensive.  I just need an amp that has an S/N ratio that is at least 100dBA like my Alpine.