Surface Spell's custom sizing

[rosedamask.livejournal.com]

Hey! :)

Does anybody here have experience with ordering custom sized items from Surface Spell? I'm in love with their Boleyn OP, but before placing any orders, I just wanted to check whether they work from the actual measurements of your body or whether they expect you to ask for the measurements that you want for the garment itself, making it advisable for me to add ~5cm to my details to ensure a decent fit? Thanks in advance!