It is possible to put the pump in either position.

If the booster pump is installed before the prefilters it will be exposed to fine particles in the water supply that can start to block the valves in the pump head. This can shorten the service life of this part but it is readily avaliable and easy to replace. If it is placed after the prefilters the valves in the pump head will be protected from any sediment but care must be taken to replace the prefilters when due. If the prefilters block sufficiently it will restrict water to the booster pump and may cause damage. It is also worth noting that if the booster pump is placed after a carbon filter care must be taken to flush the carbon block first to stop fines from the new fliter block flowing in to the pump.