Well in an ib install you are using the trunk basically as a huge box. So you need the trunk to be sealed just like you would any normal box. Or if it sound does get out it does not get back into the cabin because it will cause cancellation that will cause loss of bass, a "thin" sound etc. When a speaker plays it makes one wave that goes foward from the front of the speaker as well as an opposite one that results from the back of the cone. When these two meet they can actually cancel each other out. One of the jobs of the box is to isolate these two waves so you dont get this cancellation. The other result is that the air inside the box acts as a spring. When you go ib typically you also cut power handling of a speaker down a fair amount so you have to be careful how much power you give it. Since your not using them as subs and it looks like it has a relatively stiff suspension its not quite as big of a deal. I guess i dont see the point to using those speakers as full ranges esp when the seat is up and blocking them but if it sounds good to you then might as well go with it. Now seal the trunk off put a pair of 12" subs there and its a different story. Components just not loud enough of what?