So I have a gate valve to tee to logs to front cover and exits out the thermostat housing. I also installed gate valves on both exit points in the t stat housing. My q is, can't I slow the inlet volume and the exit volume equally so I can get a higher temp while still filling the motor completely? I'd like to see 160 I'm 120 which I believe is def robbing power
No.
Imho, eliminate the valves on the outlets.
Why are you trying to raise the temperature? Think about this.
No matter what temperature you see leaving the engine, the entering water is still lake temp.
Set the valve off the pump for 150°F at idle and leave it alone.
The 1 or 2 hp you are potentially losing its not worth destroying the engine.
GT