Theres never a set GPA, it varies depending on demand.
You need a 3 to stay at mac and a 4 to stay in Eng.
Something like Mech tends to be saught after and people use their free choice, or you have to have something like an 8. Biomed i know is really high up there too.
You'll just have to see how many other people want it as their first choice... but wait till second term