Learning counter steering and back drifting needs a bit of practice and it helps you a great deal in tough situations. But there are few myths, I will try to point out some.
Myth-1. Back drifting increases kart speed than its actual speed.
Back drifting or counter steering never increase the kart speed, it only helps you to maintain the speed during turns and it helps you prevent decreasing the speed when your kart is slowed down by lighting or UFO.
Myth-2, Back drifting cannot be done with every kart.
No, it can be performed with any kart, but the ease may depend on the kart’s handling and other things. If you observe some videos in our blog, drifting is performed with barrel karts and other gp karts aswell.
Myth-3, Back drifting is not helpful you in Power-up races.
It will be very helpful, during in powerup races aswell, you can notice the difference when UFO is thrown on you, you can maintain the speed above 130 if you counter steer.
I guess I tried to cover few myths, do add if I missed any 
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