Does not come with gasket - For Modern Gen3 HEMI's 2003+ it will require the re-use of the stock thermostat gasket or replacement.
These High Flow Thermostats greatly aid the proper functioning of a high performance cooling system. They are engineered to warm the engine to a proper operating temperature without making it run hot enough to lose power. Also the "Balanced Sleeve" design is highly recommended for use with High Volume water pumps. With other thermostat designs, the increased flow generated by High Volume water pumps can actually attempt to hold the thermostat closed. The "Balanced Sleeve" design equals the pressure exerted on the thermostat allowing its operation to be solely regulated by coolant temperature. Special Notes: This thermostat is not recommended by HHP for stock or daily driver vehicles due to the extreme drop in operating temperatures this thermostat causes. It is recommended that this thermostat be used in conjunction with fan setting changes to help in the cooling of your engine or the benefits of this Thermostat will not be seen. In cool ambient temperatures, typically below 50 degrees, you may throw a P0128 efficiency below threshold code due to extremely low operating temperatures and delays in reaching a satisfactory operating cooling temperature unless custom tuning is applied.