You should pick vehicle parts that suit your driving style. Try out different things and find what you feel most comfortable with. Combos with higher speed are generally the most common among the better players, although combos with at least 3/5 acceleration are also used. For the soft drafting: Manage to drift at the same angle as normal, but charge your mini-turbo faster. The sweet spot is found in the upper left corner for a left drift, and the upper right corner for a right drift. It is important to note that it is slightly different for each controller type, so it takes practice to find and master.