Sealed Q?

I am mostly a fiberglass builder, i dont often have to deal with this as i normally hand the boxes off and the client puts them in......so please excuse this.  I am doing my own car now for the first time!!!! :) the box is done and no air will leak from it but i have never had to set the subs in on my own before, what should i use to seal the sub on the sealed inclosure? should it be 100% air tight?

Yes it needs to be air tight.  I usually use silicone rubber cement (RTV) although many people use things like caulk or window sealant or even rubber gaskets.Support the12volt.com

@Dyohn: Rubber cemenet, or silicone; i've heard it has affects on some of the components of the sub if you use either to seal the box itself, and stick the sub in before it cures. this does not affect the sub when your using it simply around the edges for mounting the sub? is there a certain chemical that may be labeled on caulk/cememet that i can avoid?

The component of some elastomer cements that can damage some speakers (specifically those with foam surrounds) is the zylene or other ether used as a solvent to make the stuff cure.  Most good quality modern formulas (like food-grade 3M RTV) use some other chemical that is not nearly as harmful.  The silicone itself has no effect on the speaker.  I've used RTV to seal enclosures and to mount woofers for 30 years with no effects at all on any system I've ever built.  I don't recomend "rubber cement" by the way.Support the12volt.com

for mounting the sub you can buy a sub gasket for this it is a rubber gasket that will go between the sub and the box

Good weather-stripping works well too. Paul