The 507 from Gooderham to the turnoff at 36 where it ends is a roller-coaster of a road that traces the western edge of the Kawartha Highlands Provincial Park. The road surface isn't terrible (for Ontario), but can be rough in places. The highlight is 38kms of almost continuous fast corners. This is through dense Canadian shield forest and around lakes, so the sight lines aren't always great, but it's guaranteed to put a grin on your face.