I have a 2005 lightning w 2 -525 EFI why is there a 15 degree water temp and 10 degree water pressure difference betreen the two.

Sounds like one of your raw water pump empellers is going bad and needs to be changed the one with the higher temp. seems like it needs to be changed from my experince that is the reason for the different temps

I changed the pump

...and the difference was still there I assume. Was the impeller in one piece???