Test driving a tuner?

and they were talking on some of the diesels if you dont wanna cuagh up the cash for a tuner they give you a free download that only lasts for 5 driving hours and then goes back to stock to helpyou decide if you wanna spend the money
does anybody do that for our trucks, ide love to test my truck out, see what a tuned 5.4 can do, but still running 87 octane tune wich may not be worth it compared to 93 becuse if i wanted to use 93 i woulda just bought a HD edition truck and got some PSI.
Anyone else heard of anything?
We've had a diesel trucks in that the owner's had done the tuner test drive and after it expired the truck didn't run like it was supposed to. It seems that when the tuner test drive "uninstalls" itself it doesn't quite put everything back how it was before. The cure was to reprogram the PCM back to the latest program.



