Below is a performance plan run by Jeppesen for an 800XP. It shows an average of 49kts of headwind, climbing straight to 380, then stepping to 400 when able, and cruising at M.70. 4 pax. Departing SFO, 120lb fuel burn startup to takeoff. Landing with 1400lbs. Not what I call a good reserve for flying 2100 miles overwater.
PLAN XXXX KSFO TO PHNL 80XP M70/F IFR 08/23/05
NONSTOP COMPUTED 0256Z FOR ETD 1300Z PROGS 2218NWS NXXXXX LBS
FUEL TIME DIST ARRIVE TAKEOFF LAND AV PLD OPNLWT
DEST PHNL 008481 06/06 2100 1906Z 027180 018699 000800 016500
RESV 000000 00/00
ALTN 000000 00/00 0000 Z
HOLD 000000 00/00
REQD 008481 06/06
TAXI 000120
XTRA 001399 01/12
TOTL 010000 07/18
CLEARANCE
KSFO..NORMM..BEBOP..36N30..32N40..26N50..CLUTS MAGGI3 PHNL
WIND M049 MXSH 2/36N30
TAS 407 FL 380/32N40 400
Now....just for kicks....lets see the return for the same time and situation.
PLAN XXXX PHNL TO KSFO 80XP M70/F IFR 08/23/05
NONSTOP COMPUTED 0305Z FOR ETD 1300Z PROGS 2218NWS NXXXXX LBS
FUEL TIME DIST ARRIVE TAKEOFF LAND AV PLD OPNLWT
DEST KSFO 007146 05/00 2101 1800Z 027180 020034 000800 016500
RESV 000000 00/00
ALTN 000000 00/00 0000 Z
HOLD 000000 00/00
REQD 007146 05/00
TAXI 000120
XTRA 002734 02/13
TOTL 010000 07/12
CLEARANCE
PHNL MKK4 CLUTS..26N50..31N40..35N30..KSFO
WIND P047 MXSH 3/35N30
TAS 403 FL 390
Hmmm....landing with 2700lbs going eastbound with an average 47kt tailwind...and you say that you can do it going westbound with up to a 65kt headwind? Ok.....whatever you say...