Originally Posted by CMS

Yep, there is a pass-through where the two pipes meet, it's difficult to see (which is by design, so it doesn't jump out at you when viewing the exhaust on the car). The pass-through is placed so that exhaust pulses cross-over just as they' begin to straighten out, so a vacuum is created in the adjacent pipe without creating turbulence, but also so that the pressure waves can cancel each other to eliminate drone.