WOW!!! Go with the Borla muffler swap!! The stock Nissan mufler is close to 3 feet long the Borla about a foot and a half so they did have to add som pipe to the system. What a difference in power, the horses are right there when I give it even a little gas! Nice sound too, not too loud not too quiet. Best purchase for me so far with the X!! The stock exhaust is so restrictive, 2 cats and that huge muffler, what a waste of power!!