This won't apply to everyone on here, but if someone you know is considering swapping out the Monsoon Audio for an aftermarket head unit/amp, they should also pony up for some aftermarket speakers. The factory ones aren't likely to last very long with an aftermarket upgrade. Here's why:

Ohms law maintains a relationship between step-voltage, amps, ohms (resistance) and watts. We all know that the Monsoon system delivers 500 watts of sound at 2 ohms. 2 ohm speakers are pretty unique and most aftermarket head units and amplifiers are designed to work with either 4 or 8 ohm speakers. An online Ohm’s Law Calculator (see link) gives us the details. If you plug in any two known variables, it will show you the rest.

Volts-Amps-Ohms-Watts
31.6 - 15.8 - 2 - 500
44.7 - 11.2 - 4 - 500
63.2 - 07.9 - 8 - 500


so we see that the monsoon head unit generates a step-voltage of 31.6. To drive an 8 ohm speaker at 500 watts requires an aftermarket head unit (or amp) with a step voltage of 63.2. If we reload the calculator with 63.2 volts into a 2-ohm speaker, we see how easy it is to grenade the whole system:

63.2 - 31.6 - 2 - 1997 WATTS! (overdriven by a factor of 4)
44.7 - 22.3 - 2 - 0999 WATTS! (overdriven by a factor of 2)

Online Ohm's Law Calculator --> http://www.angelfire.com/pa/baconbacon/page2.html