If I want to try the 91 tow tune(currently on 87 tow tune) do I have to first go back to the stock tune or can I just change over? My tuner is the Superchips 1745 which has 3 different tunes. If I can just change over, can I run the truck down to almost empyt, put in 91 octane, run that for a day (while still on the 87 tow tune), and then load the 91 tune? Would running my truck on the 87 tune with 91 octane (during this change) do any harm to the motor or anything else? Hope this makes sense and thanks for the previous help?

 

You do not need to revert to stock tune to switch to another 1745 tune. You can go straight from 87 octane tune to the hi octane tune.

Have fun!

 

That is covered right in the Micro Tuner's documentation.

Any time you want to change programs, simply plug the unit in, select whether you want to tune the vehicle or do diagnostics (selecting "tune" in this case), and then select which program you want to load - then simply load it up! No need to go back to stock first.