I went the other direction from HP Tuners nGauge to SCT. I had to go back to stock with the ngauge before doing anything with the SCT tuner. Then using the SCT X4 I could pull in the factory tune and send it off to my tuner. Funny cant recall doing that, maybe I sent him the base tune that the ngauge pulled up. Either way if he pulls whats on the car now he will be getting your current custom tune to work from, not what I think he'd want to start from.
I think as a general rule (if you ever want to go back to stock) you want the base tune on the car before you introduce a new tune from a new device, that way the new device can archive the factory tune to allow it to go back to stock if that day ever comes.
Are you going to end up with an nguage that he loads the tune with or is he doing it in person with a laptop. I believe that if he tunes directly using a laptop it loads the car with a *.hpt, if he's using an ngauge it will use an *.enc file instead. Also if it is through a ngauge, the ngauge will store the stock file off the car when the custom tune is installed the first time for later "revert to stock" action, if he does it with a laptop and no ngauge ask him how to go about reverting the car back to stock if you are interested in that. I don't think you can use your SCT "revert to stock" if the car is loaded with an HPTuners tune.
