contest with the neighbor

Each sub calls for .85 cft sealed or 1.3 cft ported.  I know 5 cube is WAY too big for a couple tens, so I'm going to downsize it.

I would like to make the box perfect.  Slightly larger like you suggested and tuned to specs.

Can you help me with this:  I would like to run both tens in one shared enclosure and do a slot port on the side.  Unless a sealed box is the way to go?

Anway, if I did a sealed box let's say, if the gross volume for 1 sub is .85 cft then would the box need to be 1.7 cft total?  Or do you calcualte it different?

Same question on gross volume for the ported box.

Then, what is the best way to calcualte the right port length?  Do you think 2" wide X16 tall will work? If so, how long?  Or, should I just do a single 4" circle port for these?

Finally, how about muliple ports?  Like 2 4" ports.  I think I'll have plenty of power to push the air.

Thanks!