Hey, that's awesome! You'll love having a Lightning, they are awesome trucks.
Mine is still stock accept for the addition of a complete Bassani exhaust system, which really sounds great on it. Some future modifications you may want to consider in addition to an exhaust is an induction kit, throttle body, mass air kit, 4# or 6# blower pulley upgrade, and a computer recalibration chip (done with a chassis dyno). You can significantly add to the performance of the Lightning with these upgrades.