Just installed the OBD Gauge P10 Pro in my 986 Boxster S. Main reason was to get oil temp since these cars only show water temp from the factory. Oil takes way longer to warm up, and I like to wait until it's ready before driving hard.
The display also gives me A/F ratio, RPM, voltage, throttle position, engine load, and a bunch of other live data. It even does 0–60 and stopping distance measurements, plus it works as a code reader and live diagnostics tool.
Install was easy — plugs right into the OBD2 port and powers on with the car. I mounted it low next to the dash so it stays out of the way.
Nice little upgrade if you like having more info while you're driving.