Was climbing a hill in about 2ft of settle fluff on the side of the West Fork lookout south facing hill in the elk meadows area of Lolo pass this morning. WOW, hit a rock with my chain case hard, stopped me dead and almost went over the bars going uphill. Got off, looked the bike over, no obvious visual damage, fired her up, first second thrid then big noise and I have an exhaust leak, steep spot so I ran it 200 till I hit a road, stopped. NO HEADER ? 40 some years of biking and sledding, seem about everything fall off, never the head pipe. GONE, hour of looking, seems a red hot header in 4ft plus of snow, will go back on my sled with metal detector. Always some ting.