Just chimming in that I've been practicing/perfecting this technique on World 1-1 (halfway through the stage you can do this trick to go over the pipe and get a major speed boost for the later half of the stage, by diving off the pipe into the half-way flag and scratching just as you hit the ground, you'll keep a lot of momentum and speed).
It's really amazing once you pull it off. Funny on how the slowest character in the game can easily become the fastest 
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
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