to stack the two programs and a switcher to go back and forth. Moates.net sells both. This is useful for switching between pump/race tunes or normal/valet as you mentioned. I suppose you could even use it for an anti-theft switch and put garbage or blank data in the space for the second tune (ie. it won't start unless you switch back to the working program).
________________________________________ NA to TT, starting from the ground up...