I found a great way to return the shine to the exhaust header pipes on my 2013 Griso, Blue Magic Metal Polish Cream. I previously tried Barkeeper's Friend and it took off the golden color but it's abrasives are too coarse or too hard, and it left the pipes clean but cloudy. Blue Magic works great, takes off the golden color and restores the polished metal look. I used a micro fiber cloth and lots of elbow grease. I got the cream at Autozone.
Here's a pic.