Urgh...
Guys, try keeping a boa before spreading bad advice.
BCI RARELY exceeds 7'; even Colombian. You get a few oddballs that are 8'-9', but there are not very many that are 10' or more. Even Red-tail boas have a hard time exceeding 7'-8' long. Out of all the boas I seen, the only 9' one I seen is a 30 years old female; there was a few 8' I met, but they were far and few. Most are actually 6'-7'. However even a lot of the Colombian boas are Central American mutts that been exported out of Colombia, rather than being from Colombia instead. Back in the '70s and '80s, there were huge demands for boas, more than Colombia could harvest so they began exporting Nicaraguan, Honduran et cetera as Colombian since back then people viewed Central American boas as worthless (just like how non-Cuban cigars are "worthless".)
Central American BCI tend to stay under 6', however that is only assuming they are pure. However depending on the locale, they can either be nice or really nasty.
If you don't want a 7'+ snake, I would avoid female boas, coastal carpet pythons (other carpet pythons are okay), water python, reticulated, all scrub pythons, sans Tanimbar Island Scrub, and a few I am forgetting.
In the hobby, it's easy to get into the "I caught a fish THIS big" mentality.