and also is it worth doin?
Absolutely not.
I did 4unit in high school and when I went to the first MATH1110 I laughed at how easy the stuff they were doing. I think the first lesson was trig revision, for god's sake! In my arrogance, I decided to kick is up a notch (BAM!) and do the hard maths, but ended up regretting it.
There is absolutely no need to give yourself the extra work. You won't be better off for the harder courses, you won't get a better job, etc. You will just be taking the hardest path to get the same result.