Becoming a Wonderbolt Reserve is probably the best thing that's ever happened to Rainbow Dash, and she doesn't want her party celebrating it to end. Fortunately Pinkie Pie won't rest until Rainbow Dash decides the party's over. And she hasn't said that yet.
But how should two ponies carry on partying when the rest of the party has gone home? Pinkie Pie knows the answer: a race. In the end there's more on the line and on Dash's mind than simple celebration or victory, though.
Cover art by mister-hand. Regrettably their DeviantArt account is now inactive.