I'm gonna be running a single 12" in a custom enclosure in the trunk of my '98 Civic. The sub will be firing up from the floor. I'm contemplating venting the trunk... any thoughts on this? If I do it, I've got two locations in mind.
1. The rear deck - I could easily add a couple of slots
2. The rear seat body trim - with the trunk being open up to here, makes sense.
I'm keeping the rear speakers but I was planning on doing something to isolate them from the trunk. Building a small enclosure around them or something. I did this before but the box was ported and I ran the port directly into the cabin, but this is a sealed box. Sounds like I need to do something, just what is the best one.
What application will the rear speakers have? Fullrange, midrange, low output midrange rear fill? I ask because assuming the rears are 6.5" you are going to need a significant enclosure size just to get down to 80Hz. And this is if you use a home driver that is designed for a small enclosure of ~.3 cuft., I don't think a traditional car audio driver is going to integrate into that application well without having a huge bump in the 100-200Hz range.
As or venting, I would maybe cut out the metal back center area of the back seat, where the ski pass through would usually be. Then cut away enough foam to help the bas get through. This is assuming no one will ever sit in the middle. If not then you might want to fabricate a metal grate basket of sorts to support that area while not obstructing the bass.
I'd look for something like a Seas 7" Coax from Madisound which will work in a sealed pod of less than .3cuft. and will get down to ~80Hz. They also sell a custom passive for them IIRC.
I'd also vent the rear deck in between the pods. But instead of cutting away metal, I would drill a bunch of ~3/8-1/2" hole to make a grill out of that area basically. That way you get the breath through properties while maintain more of the structure integrity of the rear deck. You'll need a good bit and sharpener to make the job possible though.
The rear speakers are for full range rear fill.
I'll be using a Boston Accoustic 6.4lf which would take an enclose of .25 cubic ft. I don't see me cuting the back of the seat up as I do need to haul my kids around from time to time but I'm really liking your drilling multiple holes.