Aftermarket decks put out, on average, a third of their peak rating in RMS power. When Alpine says their radio is 50x4, that's peak power, count on it having about 15 watts RMS. The power they say they have is their peak power output, which isn't nearly as important as RMS power. Deck companies tell everyone the peak power rating because it' a bigger number, and they depend on the uneducated public not to know the difference.