I'm not clued up with polar FIS. Does it require both high-line cluster and multi function steering wheel? Or just the cluster and control via wiper stalk buttons?
I'd briefly looked for an OBD gauge solution and stumbled across the "P3" gauges - obd based with a small screen integrated into the original air vent on the right hand side of the dash. Bloomin' expensive though, especially for something not as nicely integrated as the polar option seems to be.
Just the Highline cluster. A ball ache to fit. It basically replaces the factory CAN-BUS box, which to get at, necessitates removal of the wiper mechanism to get at the access panel on the scuttle panel. Some people claim to be able to get at it from underneath inside the car, but they must be contortionists with tiny hands.
I sold my Polar FIS shortly after getting it. The main reason was the highline display is too laggy to keep up, especially when cold. Trying to watch boost and lambda activity was too blurry. The display was never designed for that refresh rate in mind. An analogue gauge is way easier to read, but gauges clutter up the cabin and take your focus away from driving.
I like those P3 gauges but as you say, big bucks. I'm not convinced they would survive the extremes of hot and cold from the HVAC system for long either.