The can am cooling system comes factory with a bypass on the cooling system. This bypass can recirculate as much as 40% of the coolant back through the engine/radiator. This kit allows one way flow (like any normal cooling setup). Some people will say you need the thermostat, keep in mind, an engine will run at a normal operating temperature regardless of when coolant starts flowing. The only thing to keep in mind when NOT running a thermostat, is to allow your engine to warm up to operating temperature before riding.6061 Billet Aluminum.Lifetime warranty.