Actually, I did not pull it out of thin air, I used the info I had, but I accept your info is likely correct, but it has made no significant difference except to minimally reduce the power handling with the lower number. This xmax is not worth arguing over, as it has no practical significance. If you don't high pass the driver as it reaches its excursion limit, then you stand a very good chance of ruining the driver. Look it up, sealed designs need low and high passing and all commercial sealed designs have that, and plate amps for sealed designs also have that ability. This is part of speaker design 101.
