porting backdash

wat's up guys, i'm a car alarm installer for quite a while now, but i'm totally a novice when it comes to audio so excuse me if my questions seem to lack insight or they're just straight up stupid. now to my question, what's the purpose of porting a backdash when installing a sub in the trunk, i've seen it alot in cars but never knew why.

The only stupid question is one not asked in my book. We all have something we can learn. With out asking we would never gain knowledge. I think sound is right on this one. Most the time i see this done is because there is no better place room wise for a port or to try and get sound into the cab because the trunk is sealed off.

"Most the time i see this done is because there is no better place room wise for a port..."

I hope someone's not talking about directing the enclosure's port into the cabin while the woofer fires into the trunk!  I believe the thread's question is about the practice sometime of making an air pass-thru from trunk to cabin.

Let's get terminology straight here to avoid confusion.  Don't call this opening through the back a "port" because people then think they can run a PVC port tube out the back of the sub box and through to the cabin.  The enclosure, if vented, has a port.  But if you make a hole through the back seat area somewhere that is not a port.

If it's to be done, the hole should be large enough to be nonrestrictive to airflow.  It should not be made of PVC pipe or some other structure that contains a volume of air...because then it would be a second port and the entire trunk would then be part of the enclosure.