3500kg it is.
For me 3200kg was sort of a limit (alarm bell) since we did not had a refeuling probe installed.
If you remove the wooden floor, the netting, spare oil and tires, tow bar, cable restraints, fire extinquishers, portable oxygen bottles,life vests, and the very handy APU you will get to 4000kg.
We operated with the German LBA approved mass and balance specifications and I absolutely cannot recall this number of 4000 kg.
Maybe Swiftair should talk direct to the lessor Boeing Capital.
I am shure the maintenance company Cirrus will also have some answers.
It would be more appropiate to contact these companies.
Sincerely G.J.S. Groenendijk