My port cutout and the ID of my port tubing are both equal to 2 1/2" as opposed to the 2 3/8" in the original design. Not much of a difference, I know, but as I understand it, to maintain a given tuning frequency, an increase in the port diameter dictates that the port length should also increase. Any thoughts on mounting a 3" length of my 2 1/2" tube on the backside of my 5/8" baffles, and flaring the front side of the port cutout using a roundover bit?

My reasoning is by increasing the length of the port from 3 1/2" to 3 5/8" I would be compensating for the increased port diameter, and by flaring the front of the port, I would be adding a bit more to the air volume "inside" the port. Plus, the flare might look kinda cool

I have a lot of time and several pesos invested here, and like I said a few weeks ago, I don't want to muck things up. I have some basic test equipment, namely a digital multimeter and a synthesizer that I can use as a signal generator. I also have Dickason's LDC, so I can probably figure out how to measure box tuning frequncies and stuff. I'm not looking to improve the original design, just to match it as closely as I can with what I have.