I can’t speak to the accuracy or lag using a Scangauge or an OBD2 gauge like the P3, but I can say that I’ve always kind of wanted a Scangauge 2, and the P3 that Mariokart has in his countryman is really nice. I’ve used an OBD2 dongle with the dash command app, as well as a fully mechanical boost gauge and the one I have now, which is a digital gauge that has a bar dial and a digital number readout. It hooks up to a boost tap like a mechanical gauge, then has an electrical sending unit. Dash Command is terrific, because you can customize your gauges however you want and can data log as well. My only problem with it is reading boost. It’s very accurate as far as I can tell, as it reads the PID info right from your MAP sensor. My issue was the lag. It’s just not fast enough in real time for me. The mechanical gauge I had was garbage. The needle bounced a lot (I’ve learned since how to fix this), it seemed to be off by almost 5 psi, and it was noisy! In the end I settled on a Prosport EVO digital boost gauge. I’m quite happy with this one. It reads fast and accurate, and looks pretty sharp too. No lag, and checking it against the dash command boost reading, it’s dead on with it. So now I have a good gauge right there on the steering column by the tachometer for boost and my phone running DashCmd in a holder on the CD player showing me water temp, AFR, fuel rail pressure, timing advance, etc. I’m pretty happy with the set up this way, and it works really well for me.

The gauge is totally readable. I’ve seen some reviews that claim that it’s hard to read in the daytime, but I don’t think it is at all. It did have a tiny bit of glare, but they have a visor they sell too, I put that on and it works great.

That looks sharp!