are they the jbl 10s in your sig?
if so i cant see them being much more than .1 (they def arent .05)
my sundown SA8s are ~.1 and the mag is massive for an 8 so for a close guesstimate i would use .1 or so that is for each woofer so you would be at ~.2
you should be ok volume wise with what you have you just have to watch out for the tuning just put .2 as sub displacement and see what happens to your tuning those subs will be fine if you are a tad under 2.4cuft