A flattened single or dual inlet boom tube exhaust pipe for use on race cars, such as stock cars which race on oval tracks, which mounts to the standard exhaust system pipes and to the lower frame or chassis of the car, and which routes exhaust gasses to one or both sides of the car while providing improved ground clearance between the exhaust pipe and the surface of the race track. The construction of the boom tube exhaust pipes comprise single or dual slightly flattened circular inlets which lead exhaust gasses into a flattened profile body constructed of formed sheet metal half shells, with the inlets at or above the lower plane of the body. One or more formed sheet metal structural ribs extend through the body and into the inlets and one or more spacer ribs support the half shells within the body. The boom tube exhaust pipes can be made with internal baffles or spiral acoustic traps so as to also be an acoustic muffler. Exhaust systems of the invention comprise a pair of exhaust pipe header assemblies, a pair of secondary exhaust pipes, and one dual inlet or two single inlet boom tube exhaust pipes. The invention also includes a method of construction of such boom tube exhaust pipes from sheet metal.