You'll definitely feel this one if you're running at a good pace. Apart from the grade, the narrow singletrack is easy with barely any roots or rocks underfoot to speak of.
Down South definitely isn't overwhelmingly steep, but the steady grade, repeated switchbacks, and occasional steeper section will make you feel the climbs in your legs.
From the start, the trail rises away from the access road that separates Down South from the South Connector
. Right away it level's out on a long mellow straightaway that ends at an intersection with Taylor's Trail
at a rooty turn. Another straightaway follows before it's time to start switchbacking to the top of the trail where runners will find the intersection with Upper Surfer's Way
and Lower Surfer's Way