J My MBRP turbo back SS exhuast did the same thing. Give it a few days and it will clear up. I dont know if you installed it yourself or not but when I took mine out of the box to install it the pipes had oil on and in them. I think the oil is from part of the manufacturing process.
I have the same noise on my 2001 that has only 55,000 miles on it. B20 seemed to quite things down a lot but we can no longer get it around here. I use Power Service Diesel Kleen and it helps a little. Dont you just love this ULSD fuel. If you find out it is anything other than fuel please post...