If it worked for you before you disconnected the battery, then most likely you don't have to do the mod. If your car is already equiped with "Speed Volume", you can access it by pressing and holding the power button on your radio while the power is on. One the speed volume menu appears, you can select values 0-7 of how much you want the system to scale the system's volume based on the vehicle's speed. 0 is no scaling, and 7 is maximum. I usually don't go higher than 1 in my hardtop, and 2 in my convertible. Hope this helps.