Cornwall III bass port/shelf convert to 4in round

[SkyDover]

Hello to everyone, I'm hoping to get more expert advise here with my problem. I needed some speakers for my home theater room so I purchased a used pair of cornwall III. I discovered I liked the phenolic sound better so I sold the cornwall III and I had a speaker store build them for me, cornwall speakers. He used two 4inch diam. ports by 4 1/2" length. These ports aren't working out, as he said they usually do but because I had him move the woofer up 9 inches from bottom motor board, like Klipsch did with the cornwall III, that he thinks I need to add another port most likely.

So over the weekend, I took the 7 inch shelf out of my cornscalas and put in a 9 1/2 shelf to see what it sounded like, the reason for doing this is because my cornscala has the woofer moved up 9 inches from bottom motor board too. What I discovered is this:

Klipsch had to change the port shelf for the Cornwall III after moving the woofer up because the bass chamber builds up pressure faster than it can be released. The 9 1/2 shelf sounds just like how it makes the cornwall's with the 4inch port sound, not enough air released for the ports. In Moulin Rouge when the wind mill blade passes through the view of a window.... it cannot be heard in the 9 1/2 shelf but with the 7 inch shelf it's back and can be heard, same thing with the cornwall with two 4"diam. ports. It's like the woofer is getting too much pressure build up and being choked down, I guess.

I'm not sure how to covert the 7 inch port shelf into what it would come out to using for 4" diam. ports and was hoping someone could give some insight here. Do I need to add one more port, or two? If I plug one port, the problem is worse... if I plug both, there isn't any bass. If I remove both ports out of the holes, things get a little better.

Any help would be appreciated if someone can help me out here!

Thanks, Sky