I have seen tai's over 9 feet and pics of at least one that was bigger. I have heard of them being recorded at 12 feet, in captivity however many of them have been intergraded with other subspecies and the resulting offspring are shorter as adults and have a fatter body compared to their length than purebred taiwans. My pair were neglected as youngsters (the owner fed them only one mouse a week and didn't like them because they "looked evil"
and by the time I got them they were quite stunted, still after a couple of years of good treatment they are over 8 foot and still growing.
I breed mine every year, in fact the male was starting to take an interest in the female last night...