GMC Sierra 2015 Electronic muffler for GMC Sierra, KOBY Bolt. Mashallah, its sound is delightful. With a "whip-pip" (exhaust bypass) system, empty, with a front bumper that has minor, adjustable flaws. The price of the electronic muffler is 600﷼ without the device, and 800﷼ with the device. The price of the "whip-pip" is 850﷼. The price of the bumper is 700﷼. The muffler fits models from 2014 to 2018. The bumper fits from 2014 to 2015.