If you really think about it a second you'll find out that there are a ton of goals. Things that change end goals can range from the following. Vehicle - Hatch, trunk, van, pickup with single cab, pickup extended cab, suv, boat, and many others Power - Alternator, Big 3 done?, size/type of amp, runs of power/ground Subs - Coil size, motor force, Sub size, thiele small parameters Space contstraints within vehicle - Height, width, depth. (helps to determine size and type of wood as well after obtaining power handeling) FFS the list goes on and on. So yah it helps to give a back story at least and give your own opinion sometimes. You might not always like the answer, but it will be helpful towards your final goal more often than not.