This is a good question. I figured up the cost of putting all titanium and carbon fiber parts on my 400. It would cost $3500 to save 13 lbs. I figured that if I quit eating at Taco Bell, McDondalds, Hardees...etc.. I could drop about 40 lbs and save about $3500 a year!
As far as noise level goes, I run a Pro Circuit header and silencer(Yeah right) and you can hear me anywhere in the woods ot on the track! If you want quiet and light, you better look into an XR100 because the 426 is not the place to find either. None-the-less, I love the bike and wouldn't trade it for anything! Good luck in your search.