Many aircraft have engine/prop performance information provided by the manufacture such as Bonanza, Cessna, Mooney, etc *AND* the engine manufacture. The performance or recommended settings may vary between the two-- i.e. Bonanza E-series Continental engines with Hartzell props.

Additionally there may be pilot organizations or other reputable sources that diverge from these manuals. Such as operating the engine LOP (lean of peak).

As a pilot, does one manual have legal precedence or may I choose any source of data for operating the engine and prop?