Do you put anything between the edges of the sub and the edges around the cutout of the box that makes it completely sealed between the sub and box... it seems as if you just would screw the sub down that some air would leak out around the sub. if that made sense to anyone, is there something your suposed to put between there?
Some sub manufactures supply a 'gaskit' - strip of foam wide as the sub's edge ,this strip has adhesive on 1 side & u stick it on the sub's edge all the way around & then screw in your sub like normal .
BUT - most ppl use speaker box carpet on their enclosures & when u cut out the hole for the sub ,that carpet acts like a gaskit & provides enough seal ...
Don't do silicone. Instead, order from Crutchfield, their speaker insulating rope culk. It's much cleaner as it is black and not as noticeable, and easier to remove. Wal-Mart sells rope culk too, for less. The downfall is that it is white. But if you hide it under the rim of the sub, it's no biggie, and still very easy to remove if you switch it out.
I just though I would mention too, if you are stuffing the inside of your box, to save money and get IDENTICAL effects, cut up and stuff your box with a foam mattress pad. Works the same as polyfill or Crutchfield's new foam stuff (which looks like a black mattress pad).
I'm sure someone's gonna disagree with me, but I've done this with home and car subs and the results are the same and cost half.
Well, just to make an accurate statement: The silicone will very likely damage your sub when applied like you mentioned. The reason I say this is: When silicone dries, the fumes emitted literally EAT away at anything that is foam... that includes the foam surround on your sub. Especially, being that close to the surround. However, if done carefully (only on the outside of the box - like door & window caulk is applied - you know... bridging the gap) MAYBE then, the fumes would not create a problem. As for damaging your paper cone... well, I've never heard that before. But this old dog is willing to learn new tricks! lol Hey, would an old tube from a bike tire work? I betcha it would! I'm gonna try it! I'll let you guys know. Peace.