Return the Modified Seaforium Booster to Razzeric on the Shimmering Flats.
There, I did what Razzeric wanted. Just tell him to be careful when he sets this off. If he makes the slightest mistake, he won't be moving forward, he'll just be a burnt spot on the track.
Would be a shame, too, if that happened. Who knows if our nineteenth driver would be any good?