This Walbro 255lph fuel pump replaces the OEM fuel pump. This is a "high pressure" Walbro fuel pump.
All 1999-2005 (including MSM) will require the Walbro install kit with the Walbro pump. The electrical connectors are different from the new fuel pump to the OEM clip
The 1990-1997 Miatas can install the fuel pump without the install kit. However mounting is easier with the install kit due to the new grommet. Most people also want to replace the small filter bag. The install kits for the 90-97 Miata can be found in our Fuel and Ignition category or with these links: