The stock Miata fuel pump can only provide so much fuel (tends to max out around 85 psi). We have already discussed the potential of higher fuel pressures versus higher horsepower. So, you need to upgrade the pump if you plan to fuel past 70-80psi, usually due to running small injectors on an FMU setup. Raising the fuel pressure raises the size of the injectors. Since it requires an aftermarket fueling device to control +20/30% larger injectors, adding more fuel pressure is the logical solution.
Other than that, you don't need one. If you have an aftermarket ECU, the stock pump more than enough to support 300rwhp with the stock regulator. Changing the fuel pump does nothing but flow enough fuel doesn't change any other factors in the fuel entering the combustion chamber Wholesale Cigarettes Newport.