Thats an isobaric 6th order. The 8th is with a chamber between the two individual chambers. with still dual ports using separate chambers for compression. ;D
It will depend on the dimensions and what exactly you are working to accomplish. Another style may be of better interest if I can do some calculating on it. We can talk via email and pm as we were earlier //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif. Just wanted to post on here and answer your q real quick ;D