Because it matches the front stb, it's much lighter/stiffer than what was there, it was on sale, cuz we like to mod s***, because I could, for the hell of it, so you can have something cool to check out while you change oil, because chicks dig it,lol.....but that's just me. I'm sure others would have their own reasons to do it or not do it.Are you planning some serious track time for the car? Why else would you want one?