How can one disable the speed warning that goes off and keeps beeping after reaching 120 kph in a 2005 Hyundai Elantra?

I just bought a 2005 Hyundai elantra gls and when I hit 135 or so the speed warning ing the far right side or behind the drivers side went off and so this took me about 15 hours until I figured it out I hade to disangauge the electrical plug for 5 minutes from the automatic transmission and then I undid the positive side of the batery enabling the memory from the trans mission to give feed back to the brain and then I pluged into the wire again and the I was able to around 128 but not over 130 or else your beep would come back this was done throught trial and erar vere frustrating, all I am wantting to do now is learn how to empty the tank of gas yopu know siphon the gas tank when I bigger automatic transmission comes in I am putting a Mitsubishi eclipse front wheel trans mission in but I jusy have to move the motor a 1?8 of a inch good buy??