This is what I came up with. Boost & the MPGs are necessary (they're the whole reason I bought the dongle). The G-meter, gear indicator (Yes, it works with a real manual transmission, just gotta give it your ratios), and intake air temp are nice to have around. RPM, speed, and water temp are redundant and just there to look cool/fill up space. Anything Oppo would change/add?
Also, for those wondering, I got THIS dongle. Works like a charm so far.