The aggressive behavior is your boa's only way of telling you that something is upsetting her. The move to the new enclosure is the most obvious culprit. Besides the new cage, are there new fixtures within the cage? I have witnessed many similar behaviors that can be traced back to something within the enclosure that frightens or upsets the snake. In every case, the removal of the offending object (through trial and error) corrected the behavior problems.
Figure out what is different; it could be as simple as a new hide box or water bowl, or as obscure as the temperature or ambient light being different from before. Whatever it is, once you isolate it and correct it, your girl will return to her normal temperment.
Let us know how it works out.
Thanks,
Mike Greathouse
Reptilian Dreams
Reptilian Dreams