OK, using JBLs specs of 225 liter box tuned to 25 Hz. But this is probably erronious and they should have specified the vent dimensions to get the actual tuning.

Think about it..., the dynamics of the installed speaker come into play in box tuning and how could both drivers be tuned to 25 Hz in the same box with the same vent?

2241 in green and 2242 shown in white. In a 3-way, what do you want to hear?