Hi all. I am doing an upgrade have currently 2 x 12" 1500W targa in with a 3000 watt targa baby Brat mono block. Slotted Box. And i have another amp a baby shogun 8500W mono block also targa . wondering if i should cram another set of 12" in for the 8500. So total of 4 x 12 inch sub woofers...