For sale..... Doug Thorley long tube headers with Y-pipe. I don't know the size, but it's an American company and the new price is around $5,000. It fits Sierra and Yukon with LT engines, models 2015 and newer. 3-inch catback with a full electronic muffler (Airflow). Its muffling is very good without the tips. It fits Sierra. Selling to the highest bidder. Urgent sale.