[Desi Bike]

Mine discoloured to blue patches right at the rear brake lever. I researched and found a cleaner, Blue-Job, it cleared it right up. There was a post about the mapping regarding fuel mixture, these bikes lean right out at wide open throttle. The condition is right for discolouring the you have high heat, from cat, and lean conditions from wide open throttle. I've since been avoiding running wide open throttle and have had no more discolouration returning to the muffler.

[barenekd]

The stock muffler actually has two catastrophic converters in them. I've seen a variety of different bluing jobs on them. You can see the separation of the two in the middle of the muffler with one end bluing and the other not, sometimes both ends blue. My solution was to ditch it and get a different kind of muffler to discolor. Basically, it really doesn't matter what kind of muffler you pick, it's still probably going to discolor. Deal with it however you wish. Polish it daily at one extreme, or just don't bother at all because few people really care anyway!
My EFI is yellowing at the extreme ends before and after the packing.
Bare

[Kevin Mahoney]

The issue is the heat at which the catalytic converters operate as pointed out by Bare.
Unfortunately there is no answer other than to grin and Bear it.

[Alan LaRue]

Thanks. Just wanted to make sure it wasn't serious. I can either polish it every week with Blue-Job, or call it "character" I suppose.

[Ducati Scotty]

It's not discoloration.  It's an alternative odometer that can be read from afar so that people know you actually ride the thing and it's not just for Sunday morning coffee shop loafing.

That said, I think I may polish mine out as a winter project.  This is the first bike I've owned in a long time that I care enough about to keep it shiny.

Scott

[Tri750]

A wise man once said, " blue pipes are a sign of life"
the BMW's all discolor, always have. due to single wall tubing to promote cooling and reduce weight. most, even the OLD ones are stainless or, chromed stainless to prevent corrosion,
some today are titanium and turn a weird gold color.

[GlennF]

I suppose you could always get a massive chrome heat shield made up