Took Old Si trail again for some burn. Did this one a little backwards - took the SECOND turn up Boulder trail, which is much steeper. Legs were burning before we even hit the Old Si trail. Awesome steep hike - much harder than the main trail, and almost NOBODY on it. Definitely needed the microSpikes... almost zero traction without them. We passed so many ill-prepared casual hikers once we hit the top. The mountain jays were especially friendly at the peak. Great run down in the snow.