just curious, i'm starting on my glass box for my 18" RE XXX and i'm gonna go with a ported enclosure. does the port need to be mounted flush in the box or can i make the port start extended outside the box and still maintain the same tuning (assuming of course that the port is the same size). will this work?

 

Yes it will work just fine, just make sure in your calculations you just subtract the volume of the port that is within the box, just as you normally would.

 

I'm curious, why are you going to extend the port outside the box?

 

PICS please it would look cool too

 

and why would that be?i would have thought there would be no difference as long as you take into accound the displament of the port and build you box accordingly

 

The Idea behind putting the port on the "same plane" is to augment the output of the sub in phase(let's not get into it here) with the output of the port.
BTW, "technically" speaking, ideally the port should be "on the same plane as the speaker, and half the diameter of the speaker cone away from the cone and any adjacent cabinet walls.", but that's "ideally" speaking, unfortunatly a car is not an "ideal" situation.