First of all, sick user name and picture.
Second of all, I don't know anything about applying to residency or working in Canada .... BUT why not just keep all your options open and do your best on step 1? You never know where life will take you (or where you want it to take you). Who knows maybe you'll fall in love with ortho or derm or something and want to stay in the US (or maybe a good score on step will help you stand out in similar fields in Canada, who knows?).
TL;DR: do your best and keep your options open.