I'm finally getting back to this project. i'm in the works of redoing 4628Bs the plan is E145-2118- ESS AMT-1A air motion transformer . the help I need for know is calculating the port length. what I did is carefully removed the front panel and replaced it with a new one flush mounted unitizing only the E145 and 2118 the problem was not much room on front panel for the port so I decided to side port it using the carrying handles cut outs on the side panels for the ports 2 ports one on each side . stock port measured 5 7/8 ID x 5 3/4 L i came up with 5.750 x 3.875 x 3.562 L 2 ports per cabinet my question is am i close to port tuning ? hopping Rob could shine in on this