Test 1: Shifting from 4th to 5th, testing boost in 5th with some shuttering. Test 2: On-Ramp to Freeway from 3rd to 5th. To much traffic to really test boost. Test 3: 1st to 4th sprint, full boost up steep grade onto freeway. Overboost in 3rd. Went into Limp Mode in 4th (Overboost - P0234).