A Y-pipe and flattened boom tube exhaust pipe for use on race cars, such as stock cars which race on oval tracks, which mount to the lower frame or chassis of the car, and which route exhaust gasses to the side of the car while providing improved ground clearance. The Y-pipe comprises first and second longitudinally flattened or tapered secondary exhaust pipes having respective generally circular cross-section inlet portions connectable to a header assembly and respective laterally bevelled, flattened circular cross-section outlet portions which are affixed together so as to merge together to a single outlet opening which is connectable to the inlet of the boom tube exhaust pipe. The boom tube exhaust pipe comprises a tubular inlet and attached tubular body.

A fluid treatment system is provided including a closed fluid treatment zone, at least one radiation source disposed in the fluid treatment zone to irradiate a flow of fluid, and a plurality of diffusers disposed upstream of the at least one radiation source. The plurality of diffusers define a decreasing gradient of fluid treatment zone cross-section from an upstream portion of the plurality of diffusers to a downstream portion of the plurality of diffusers. Also provided is a flat diffuser for changing flow cross section in a flow conduit.

A fluid flow stabilizer for use in a flow of fluid in a conduit between a source of turbulence and a fluid control device. The stabilizer comprises a fluid conduit section having a first end with a mounting arrangement for mounting the first end to the fluid conduit and a second end with a mounting arrangement for mounting the second end to the fluid conduit, the fluid conduit section having a fluid passage therethrough to allow fluid to flow from the first end to the second end, and a flow straightening device positioned in the fluid conduit section. The fluid conduit section may be constructed to absorb at least one of shock, vibration and alignment in the conduit.