Hi Mad M. I went against my word and purchased a Rapid Bike Easy instead of the BoosterPlug. I chose the Easy because I am going to leave the engine/air box/exhaust in the stock configuration. I like quiet.
With that said, the RBE arrived yesterday. I installed it today, paying careful attention to route the wiring harness so that it cannot be seen, nor interfere with anything HOT. I placed the control unit under the pillion seat. There is even a small cutout on the left side of the under seat box for the harness to lay/pass into the compartment. Took about 2:15 to install.
Best 200$ spent!!! As others have stated, it transforms the motorbike. It actually makes it ‘civilized’ in the lower revs of the lower gears. Everything that it should be from the factory. Of course it cannot be this way due to the very lean condition of the AFR in order to appease the emission authorities.
There was a hiccup. After starting the second time, the CEL came on. I did the 15:30 idle period to reset the ECU. Even disconnected the battery for a short while. I also turned the fuel potentiometer to +1 (down from +2). Test rode it again and it still runs/rides like a dream. After a few more engine starts/stops/ key cycles, the check engine light went out after startup.
I would recommend the rapid bike easy for a simple device to improve the ride-ability of the 390
I also had the CEL come on after installing the RBE unit.
I turned the fuelling control from +2 to +1 as you did
After a couple more rides the CEL went out and has not come back on.
The RBE still works when set to +1