4 E8v.2's ported....Enclosure help..port area??

[gps69 0]

This is going in an RX8. Looking for a fairly good ground pounder with the ability to upgrade to 4 SA8's in the near future. Not sure This design has enough port area. Don't do too many ported boxes and would like to make sure before I waste the time building. Will be powered by a Sundown 2000D.

Link to pic of enclosure I had worked up.:

[Julian 641]

http://www.carstereo.com/help/Articles.cfm?id=31

[gps69 0]

I checked that link and it appears I'll be OK with the origianl plan. Just wasn't sure I had enough port area. Was going to do a 4 SA-12 box for my son last spring and was told I needed 78"s of port area minimum for those. Didn't know how that was going to relate to the eights.. Thanks!!