I agree with Jim about the prop, a 9x6 is about right on a PAW19.
Jim I tend to run my diesels nere max but not overcompressed , i have noted different exhaust colour depending on the fuel used - kero based fuel runs clearer than fuel made with Jet A , ether content also effects the colour of the exhaust.
I have just tested fuel useing modded olive oil as lube and even when maxed out the exhaust was clear, Im very happy with the results useing olive oil.
Dont forget a motor will unload in the air causing it to run cooler than on the ground giveing an effective compression drop, so unless its pretty rich an undercompressed motor will sag in the air.
Stewart