It's all about timing man. you rock the controller from left to right while holding the 1 button and turbo.
I find it works best to let go of 1 and turbo then repeat when your truck makes a complete turn. once the front of the truck is facing foward again rock it.
I also find you have to be kind of violent with the controller. It took me a bit to get the timing right, i would suggest just practicing while racing not in the tutorial. hope this helps.