Got a great deal on an IW 10 percent lower pulley. Hoe much boost do you gain and whats the total boost on a 13 after installation. It will also be added with all other supporting mods, intake, tb, xpipe. Thanks guys! Anybody have a 10 percent over a 15. Is their any advantage? Anybody do the lower with an upper or is that a bad idea or maybe overkill for the blower?