Currently I'm in the planning phase of putting a sub in the trunk of my car. I've never owned a car that had a sub in the trunk. I've always had minivan's, trucks or hatchbacks with subs. The back seat in my Subaru Impreza does not fold down and is solidly mounted. It consists of the normal seat foam with a very thin 1/4" fiber board as a backer in the trunk. I was looking to put a Shiva Mark IV into a sealed or ported sonotube. The sealed tube would be 14"w x 14"t for a volume of 1.24cu.ft. If I go with the ported it will be 16"w x 30"l for a volume of 3.48cu.ft. Reason for 16"wide is for (what I think is) a 3" x 10" port on the same side as the sub. I can only guess at the volume of my trunk but it's probably around 25cu.ft. My questions are: 1. Being that the sub will be in the extremely small trunk am I going to lose the cabin gain that I would get if the sub were in the cabin with me? Or will it be vice versa and I'll get more gain because of the smaller enclosed area the sub is in? 2. The sub will be pointed directly at the back of the back seat. Will the seat foam absorb a lot of the bass and basically muffle the sound? 3. Because of the seat foam and small trunk area which sub alignment would you suggest I go with? 4. Will a solid 300w RMS be enough for what I'm looking to do? My music tastes are eclectic. They run from Country, to Metallica, to Electronica/Techno, to extremely Bass Heavy like Techmaster PEB (for the ultra low fix I need sometimes), to my Telarc classical CD's. I've had MTX subs that were kinda muddy with kick drums but would shake your cheeks during the really low stuff. I've also had Infinity Beta 12's that did a kick drum justice but just wouldn't go low enough for me. I appreciate any and all input.