Where I'm confused is that I understand when bridging the amp with 4 ohm speaker it sees a 2 ohm load at each terminal, but since its now one channel is that a 4 ohm load.

No, the idea is that each of the two output circuits in the amp (that would correspond to the two channels in a stereo hookup) will see the 4 ohm load as if it were a 2 ohm load. The reason for that is that for a given output voltage twice as much current will be drawn by the load than if the same voltage were being output in non-bridged mode, since in bridged mode the "other side" of that load will be a voltage that is equal in magnitude but inverted in polarity, rather than being zero volts (resulting in twice as much voltage being placed across the load).

Per Ohm's Law, resistance = voltage/current. Therefore if a given voltage produces twice the current, it means that the resistance seen by the source of that voltage has been cut in half.

As I look in my manual it states that the amp will do 600 watts into 8 ohms bridged and 900 watts into 4 ohms bridged.... when they state the power at each load are they referring to a 16 ohm speaker on a bridged amp is now 8 ohms and a 8 ohm speaker is now a 4 ohm load.

No, they mean that when connecting the bridged amp to a single 4 ohm speaker it should be able to produce 900 watts. How true that may be, or how good the resulting sonics would be, I have no idea.

Regards,

-- Al