Probably going to pick up 4 15" SD2.5's for my project. The 8" idea went out the water. Looking to get a size idea for the enclosure. I'm going with either a wall, or try to stay beneath the window. Vehicle is a first gen. 2 door Blazer. All I need is the front driver and passenger seat. What would you all recommend for enclosure size? 12CuFt net?