The more bends an exhaust system has the quieter it will be. The X pipe does have a noise cancelling affect as it eliminates the pluses from either side of the exhaust, actually cancelling them out. The X pipe is used in a lot of performance builds as is aids in exhaust savaging as well. Of course the larger the diameter the more free flowing an exhaust will be, that too can be over done, most engines operate well with some back pressure.
