I found the Answer - Bridging lowers the Impedance by half (BD-Design)

by Kevin , Minneapolis, Tuesday, August 14, 2018, 17:29 (2074 days ago) @ Bert

After a bit of googling, I found my answer the Bridging of an amplifier cuts the impedance in half. So in this case the 4ohm load is 525 Watts. When you bridge the amplifier the Ohm load is seen as 4 ohms. So, 2 X 525 watts = 1050 Watts.

https://www.researchgate.net/post/Why_do_bridged_amplifier_outputs_see_half_the_load_im...