I have a pair of JBL 2245s in 8 cubic feet boxes with two 6" dia ports 12" long this is giving me about 32 Hz from the ports measured.

It seems that I could increase the length of the ports ( easily done) by up to 14" but what is the best low end for the 2245?

I lined with Lambs wool as I found it far more effective than Fiberglas and no issues with glass dust.

Ok done some research and 25Hz to 28Hz seems optimal?