No lines would ever be needed. This looks amazing as is, like a painting but with much, much sharper detail and even more fun added to it. There are so many reasons why Pinkie Pie could be sitting the wrong way (thinking it's how to do reverse, looking back to watch her competitors, etc.) but no matter what it is a very Pinkie thing to do. The streaking, exhaust and wind in her flapping long hair add the true excitement of speed, even beyond the intense excitement on her face. You did an amazing job picking and using that angle, and dang that's one sweet looking little go-kart.