My old Brit bikes have just a terminally ill oil light and not wanting to permanently mount a gauge I built an LED RGB oil light that displays the pressure as a different colour for each range of pressure. It uses a MEMS sensor and micro-controller to convert the pressure into a colour signal. The sensor housing is about the same size as the switch. For the Boxster I would make a tee so the original switch can be retained.
Below the switch pressure it flashes red. Next range it shows steady red, then yellow, then green, then aqua, then blue. If the sensor or wiring fails it flashes white.
It updates every 1/4 second and averages the new value with the old to dampen fluctuations. Here are pictures of the light, sensor and output:
Would there be any interest in these?
I could also add a battery monitor that would show steady white for a second every 5 seconds or so if the battery is below charged voltage (12.6 volts).