I have a 05 sti and Im running ap stage1 map, my friend has a 05 sti and wants me to put the map on his sti. I was told that u cant tune 2 cars with the same acessport. Something about the ap learning ur ecu...i dont know, anyone know of this? thanks

Yeah they are coded or something and only work on the car that it is flashed on. If your friend wants to try it temporarily then you can flash your car back to stock then it will work on his car. just make sure this is really a friend so he doesn't disappear.

No. Won't work. When you initially flash your STi with the AP it "marries" itself to that ECU. You could "umarry" it by reverting to stock but...what's the point?

PLEASE use the search feature on these forums. This question has been answered many times. If you dont understand how the accessport works, should you even be using it?.