exhaust somke coming out of both thermostst openings

[Bosunsmate]

Have you got your old impellor? If so put it back in and retest

 

[Bosunsmate]

And compare their vane sizes

 

[Faztbullet]

I pulled down lower unit and unlocked the impeller key and let the drive shaft drop what little play it has which makes impeller go back to its normal position in other words a normal water pump installation and forgetting that last step in the brp installation packet

All this does is to ensure is wedge key is fully inserted in impeller do to o-ring under impeller now. This impeller is trapped and cannot move in housing so its always in a normal position. This has nothing to do with your pressure problems and yes exhaust gasses will come out t-stat holes till block fills. Install the new style ficht saltshaker t-stat assy"s and go fishing...