Cut through in a truck??????

Each vehicle is different, some will be fine others won't. Its all a trial and error kind of thing. You might not get it right the first time but if you keep trying I am sure you will.

As already stated make sure you have a big enough hole so that they can "breath". 4 15" drivers is pretty big so you need a big hole.

First we have to see how big you need. So we take the radius of the sub (roughly) 7.5 inches multipled by itself times 3.14 so....

7.5 X 7.5 x 3.14 x 4 subs = 706.5 sq inches

So now you know how big the hole you need is you can start planning.

Good Luck.

Javin's right. Your subs are going to move a certain volume of air. The larger the opening for it to pass through, the slower it can do so. This is called port velocity. It's the same reason that vented boxes require larger (cross-section) ports for higher output subs. Too much air passing through too small of an opening will travel too fast, and cause audible turbulance or a "huffing" sound. You may still feel wind, but you won't be able to hear it. And no, the back seats will not destroy your SPL.

Sub woofers wave output is omni directional wave that is VERY hard to stop. The worse problem you could have from your seat is the frame buzzing or vibrating causing audible noise. Make sure it is secured well, and keep bumping!

Make sure the hole you cut-out is about the same size as the total surface area of all your subs added together.

The 'windy' feeling is just sub-bass, the bass so low humans can't hear it but they can 'feel' it.

Good Luck!