I've read a lot of post of people complaining that their Yoshi case savers have faded. I don't know if any of them have contacted Yoshi about it or not so I figured I'd post up my experience.
I bought a Yoshimura R77D (carbon fiber) full exhaust system from Motomummy about a year ago. I noticed that the end cap was slightly faded. Nothing bad, but I'm pretty anal. I emailed Yoshi and explained to them that the end cap was faded and I was wanting to know if there was any product (polish, etc) that they would recommend to clean it. I got an email right back basically saying that he didn't see anything in the instructions about it but he'd set up an RMA. I could pull the muffler off, ship it to them, they would inspect it, repack it and replace the end cap. I could do it now or if I wanted to wait until after riding season was over, it didn't matter!
Many companies would probably try to get out of covering something, that's not what Yoshi is doing.