flyingfemme -
The ones that I have been acquainted with had a demand O2 system with enough for a single pilot to empty the drop tanks and adequate for two under about 20,00 feet. We did some serious touring.....
Is that the Tuc you're referring to or the Pilatus? My own acquaintance with the Tuc never extended to seeing any with drops tanks. On your "serious touring" comment, can you expand at all? I ask because this would be my main usage if I ever bought into one.