Amplifier, Alternator Power

To start here is the amplifier I have. http://www.crutchfield.com/S-bxEvOAaPI3Q/cgi-bin/ProdView.asp?search=ap2000&i=489AP2000

I have it hooked up to two DVC subs hooked up at 2 ohms each.  The amplifier outputs 480 watts RMS x 2 at 2 ohms

In the Crutchfield Guide to Car Stereo Installation there is a section which describes how to estimate the current demands of an amplifier.  It first says to multiply the number of channels of the amplifier by the RMS watts per channel (2 x 480= 960).  Double that number (960 x 2= 1920).  Then divide by 13.8 (1920 / 13.8= 139.13)

This is the system’s approximate current draw in amperes; let’s just call it 140 Amps.

To estimate the reserve current capacity, the guide says to take the alternator’s amp rating and multiply by 40%.  My alternator is rated at around 80 Amps.  When the math is run (80 x 40% = 32) it shows that there are around 32 Amps left to power my audio system. 

This is REALLY low compared to amount of power that the amplifier should be able to pull.

My question is Will this make any real difference?  I know that capacitors can help in some cases, but in this instance the difference between the alternator and the draw of the system seems quite big.  Other than upgrading the alternator, is there anything else I can do?

Also, Can this under powering cause any damage to the components?