So, at ~1100 lbs dry, how do you add 452 lbs of fuel(42*6), 380 lbs passagers( 2*190), and 100 lbs of baggage and be within the 1800 lbs limit. Above totals 2032. Even at 1050 dry you are still at 1980 lbs
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not sure your point about the math, it doesn't answer my question
42 Gallons (159Lts) of fuel weighs 245 Lbs using a SG of 0.7, so...

1050 BEW + 380 (crew) + 100 (crews things) + 245 (go-go juice) = 1775 Lbs, or under the 1,800Lbs limit for a -8