I notice consistently in the aftermarket exhaust world that in the majority of cases, when a longtube is placed on an engine the low to mid-range power picks up. This is also with the same size diameter primaries but different lengths. So I am comparing: Long tube: 30" primary tubes into a 7-10" collector before going into mid-pipe. Short tube: 10-12" primary tubes into a 1-2" collector before going into mid-pipe. Why do longer exhaust primary tubes create more torque and low-mid range power?