It is certainly possible, but it’s likely that you also need to change the burden resistor(s) in your Pi.
The front end of the emonPi is nothing but a cut-down version of the emonTx V3.4, so the calibration data for that applies equally to the Pi.
The easy way is to change "scales = " in emonhub.conf, and that’s something that you can do with your web browser. The harder (but in my view more ‘correct’ way) is to download the sketch from Github, edit it, compile it, transfer the compiled file to your Pi and then load it into the Atmega 328P via the serial link. That is documented - in the Wiki I believe. If you can’t get unity power factor with a purely resistive load (which will be because the phase error in your CTs is different), then if this matters to you, you’ll have to go down the hard route.
