Extending slot port past the exterior of the box

[BYTizzle]

I sold my Benz and bought a new M4 last week.  I want to install my (1) 12" sub and Skar 2000.1 in this car.  The box size needs to slightly change from what was in my Benz but this gives me an opportunity to tune it a little lower to try and pick up some more sub 30hz response.  It was tuned at 33hz in my Benz and honestly sounded really good.  Below 30hz was a bit weaker, so my thoughts are to try and drop the tuning to 30-31 area and see if I like that better.

Going off of the dimensions I have Im only able to drop the tuning to about 32.5hz area before I run out of port length.  This leads me to my question:

"Can I dimension out the box and calculate port length and net volume with a standard port and then make a 2" piece extend past the face (rounding off the edges to make it look somewhat nice still) to get the port length I need to drop the tuning frequency more without losing more net volume?"

In my mind, it doesnt seem like this should effect anything other than port tuning but I just want to be sure!  I appreciate any help or insight!

Edit: After doing some plotting in Term Lab it seems I will lose a lot of output in the area I typically listen to to try and force some 28-30 hz output.  Not sure this is worth trying honestly now.