Difference in 2 and 4ohms is 2ohms, difference in 4 and 8 ohms is 4ohms though //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gifbecause you only gain 100 watts when you half the impedance
200x2 @4 ohm
250x2 @2 ohm..