Stat170 is pretty basic, its not very hard at all BUT...
you need to attend your lecture and all your classes. You buy a textbook *quite useless* and a folder. The folder has EVERYTHING very clearly of what you need to know, its basically the entire semesters lecture slides. I ended up with a very high C, but i went into the final on a D average. I did 2 unit maths at school and was not 'top of the class' so don't feel like you 'need it'.
In fact, i think you'd probably be ahead if you had done general, as theres hardly any stat in 2unit.
It does appear overwhelming to begin with, but they go through everything, how to do it, what to apply etc. in the lectures. If you follow it its definately not hard to pass...