To be rewarded with a music player that allows you to change songs while driving, find the Mouth of Metal upgrade near the beginning of your adventure. In The Deuce, look for red flowers around a mettalic structure. These are entrances to Motorforge. There is one located northeast of Bladehenge and another on the northeast side of the mountain where the Kill Master lives. Play the Relic Raiser Solo nearby and you can drive in with Duece. You will be rewarded with the music player.