Ok so can someone explain to me the diff between the S4 and S5 side housings? As well as the S4T2 and S5T2 side housing? Looking to get new aluminum side housings for the 13b, but im not sure the diff between S4 and S5. If i ever figure it out, it'll be a turbo build. Also, after looking on Mazdatrix, they had the aluminum side housing for the front rotor and the rear rotor as well as a front, intermediate, and rear housing.... WTF is all that about? Someone help me out, im confused and my head hurts