The largest boa i have ever seen was a 12fter.It was huge and very well taken care of.If you do get a boa buy a pair of welders gloves to use when you are taken it out of its home.If it does decide to bite you you will not feel a thing unless he goes higher up .I had a 9fter and she thought everything that entered her home was food .I never felt any of her bites,and they realize that your not food after a second or two(gloves taste nasty lol).