Must use with electric Waterpump! Install these plugs to remove the OEM Waterpump assembly. The OEM shaft/seal and bearing cause parasitic drag. Dyno testing shows a repeatable 0.4hp to 0.5hp gain. The electric pump is far more efficient at cooling the engine as well. We designed these plugs so you can easily remove them and reinstall the OEM mechanical pump. Complete kit with aluminum plugs, O-rings and stainless circlip. We recommend using a Bosch electric Waterpump with the Twisted Development Pump Housing/Mount and wiring adapter. Plug and play! Features -Aluminum for corrosion resistance and lightweight -Can be removed easily -Extra O-rings and circlip