A lot of people on here have tried it and it does seem to make a slight difference on the K3+ bikes.
It's not really worth buying one of the G-Pack style boxes though, as they're very overpriced, as all they are is a resistor in a plastic box!
A while ago, I put together a tutorial on how to make your own for just a couple of quid!
Looke
here and scroll down to the "
How to do the TRE mod on an SK3 and above SV" section.
HTH