I was kind of disappointed when I realized the R3T did not have a tach. Whoever heard of a performance machine without a tach, or maybe I am just spoiled by having a tach on every vehicle I have owned since 1973.
Anyhow, after looking around, I decided a GPS with OBD Bluetooth technology would probably work good enough for the type of riding I do these days. So after looking at different GPS units I decided on the Garmin Nuvi 3490 with the EcoRoute app. With the GPS and a transmitter plugged into my OBD plug I had gauges. I was a little worried at first that once in the sunlight it would be hard to read, but it does pretty well. In direct light, with tinted shield and sunglasses I can still read it well enough for it to be useful. I seldom use the GPS function, other than the other day and I realized my speedo is right on with the GPS mph readout, but the gauge speedo in the GPS is about 6mph low (?). I am going with the GPS and speedo, cross checked several times in the last two weeks with those speed readout trailers they put on the roadside, my speedo, gps and trailer were all right on with each other from 35mph to 65mph.
To wire it up was stupid simple, I just ran the wire for the power cord to the battery. This winter will be a terminal block for it and my horn, and whatever else I may put on there. The RAM mount I am using mounts the Garmin GPS power module into it so all I have to do is pop the GPS out of the mount and not worry about plugging and unplugging everytime I take the GPS off. As far as I can tell, there is no parasitic drain on the battery when turned off, Garmin wouldn't tell me one way or the other. They just wanted to tell me warranty was not good if used on a motorcycle, after all, they have more expensive ones for that.
It will even work as a GPS I suppose.
bob