Hi GM!
ok. I've done some simulations as you can see in the picture. I think 200litre is the maximum I can tolerate since I live in an apartment now. Crossover frequency is about 80 Hz. To me, it seems like there's no point going larger than 200litres. I only gain about 3 dB in maxspl 20-25Hz by going to 310litres and the loss in magnitude for the smaller box is not a problem since I'll use an equalizer for room compensation. I'll probably have +-10dB peaks in the bass anyway I've got two 2240s so maxspl should be atleast 116 dB, right?

Does it seem reasonable?