enclosure design/vibration issues

Appreciate the response, when you say smooth the port, should I take sandpaper around the edges to more or less flare it out evenly?  And adding cross braces may be a pain at this point with all the wood glue, torx screws, etc, but if it will help substantially I'd be willing to do it.  The box is all 3/4" MDF btw, and out of curiosity what effect does it have on which sub I wire out of phase(inverted, or non)?  The port terminates 2.5" from the rear wall of the box also,  and what exactly do you mean by terminating into the shared air volume of both subs, just equally? - Anyway, a lot of that would probably be a pain to change, I might as well build another one opposed to all these modifications, I might just run out and get another sheet of MDF, I definitely appreciate the help, keep it coming :).

Jeremy

You can't use the 180 switch because it reverses polarity on both subs that are hooked to it.  You can change the wiring polarity on either of the two subs, just as long as one is opposite in polarity than the other one.  Once that is done, you should experiment with the 180 switch to find the best overall phase (output) with the rest of your system.  About the suggestions I made, I thought:  1.  That you were already going to build a new box, and 2.  That the pic made it look like it was built out of 1/2" stock.  Bracing would be a big pain to do in this finished box.

As for flaring the opening:  as it looks now the opening is squared and looks a little rough.  Putting a nice roundover edge on it will smooth port turbulence and lend a more professional touch to it.  Fb won't be affected.  But 2.5" is a bit close to the back wall, IMO.  There is an amount of airspace needed at each end of the port that actually functions as part of the acoustic port length.  The general rule of thumb is to leave the equivalent of the port diameter (when talking about a round port) to be sure you've allowed for ample space for true port function.  Since the equivalent round port diameter is much wider than the narrowest width of your slotted port...it would be in the neighborhood of 5 or 6" I would guess...I suggested a bare minimum of 3 or 4".  I would design it to leave 5 or 6", and that would be determined by finding the equivalent round port diameter first.

And you know you must do something about that wiring coming out of the port.

Ok, subs are already wired properly then.  And yep, a port is a port.  Here's an illustration of the acoustic port length vs. the actual physical port length:

I don't know any math to calculate the actual space needed, so I just use the rule of thumb I mentioned.  What you have may be enough and it's not something in itself to have to build a new box to change.