ACCORDING TO THE OPERATOR, CYLINDERS HAD RECENTLY BEEN REPLACED ON THE ENG & PLTS HAD BEEN INSTRUCTED TO OPERATE THE ENG AT 75% POWER WITH THE MIXTURE RICHER THAN NORMAL DURING A BREAK-IN PERIOD. ON THIS FLT, THE PLT TOOK OFF WITH A FULL LOAD OF FUEL. AS HE APCHD THE VICINITY OF ATHENS, GA, HE INFORMED ARTCC THAT HE WOULD LIKE TO DIVERT DUE TO LOW FUEL; HOWEVER, THE CLOSEST ARPT WAS BELOW MINS. THE NEXT CLOSEST ARPT WAS HIS DESTINATION. WHILE BEING VECTORED FOR AN ILS APCH, THE ENG LOST POWER DUE TO FUEL EXHAUSTION. DURING A FORCED LANDING, THE ACFT HIT TREES, THEN CRASHED TO THE GROUND. THERE WAS MINIMAL COMPROMISE OF THE CABIN AREA DURING THE ACDNT; HOWEVER, BOTH OCCUPANTS DIED SOON AFTER THE ACFT CRASHED. THERE WAS EVIDENCE THAT BOTH OCCUPANTS HIT THE INSTRUMENT PANEL DURING IMPACT. THE PLT HAD BRUISES WHICH WERE CONSISTENT WITH THE USE OF SHOULDER HARNESS, BUT THE PASSENGER HAD NO SUCH BRUISES.