boxdesign

To help me better understanding box building I tried to input my box design I purchased but the design input doesn't match my designer's specs. slot port length is exact but the app(s) say 33 Hz, I was told my box is tuned to 40 Hz. I was also told I have 1.4 air space but the app(a) again say...

I have 2 Kicker comp Rs in separate prefab enclosure. they can't hit low and are very peaky..im looking for a good box design with a big port in the middle. Ive looked around a lot online and haven't been able to find anything specific other than http://www.caraudiofabrication.com/box-designs ...