The Sonorans stay 4-5 feet as adults...they are a dwarf subspecies. All of the Central American BCIs stay around that size as well.....Hogg Islands, Nicaraguans, etc......and yes, BCCs ALL get big and they are NOT a good first boa. They are much more temperamental than BCIs and much less hardy. The only drawback of the dwarf BCIs is that they tend to be very temperamental also. I have a pair of Sonorans and the female is very hissy and aggressive. I'm sure you could calm them down over time, as long as your willing to take a few nips, lol.