Harnessing Exhuast Heat

Guten Tag to the forums! My latest idea is harnessing exhaust heat and using it for heating a travel mug! As fall descends upon rainy Portland, the usually unwelcome exhaust heat becomes my best friend while idling at stoplights, and I thought I could put it to a better use! If I was to redo my exhaust with a V split in it, I could route some of the exhaust to a smaller, coiled copper tube that would wrap around the cup holder on the bike. Using a steel travel mug, the heat would transfer from the coiled copper tubing to the mug, thus warming the liquids inside and keeping it toasty for a long, cold ride! I also suspect that if I was to run all my exhaust through tubing in this fashion, my bike would become VERY VERY quiet, a possible positive double whammy! Thoughts?

Exhaust split sounds good to me! I suppose the very end doesn't get very hot, but my hope is that a smaller pipe will help focus the heat through the entire coil. Haha don't worry, I understand that a two horsepower magneto couldn't power a medium size electric motor, let alone a watt-sucking heater!