Well last night we installed a stainless SuperTrapp muffler on the Volvo V70XC. Simply cut the old rear mufflers off and welded the SuperTrapp in the spot were the first muffler goes. It was pretty simple really. Might need to add a hanger on the right side of it to pull it more to the center of the opening but it is secure where it is. Give a listen and let me know what you think. http://www.youtube.com/watch?v=eQIhhwwV69k
I think it is merely condensation. When I cut the old mufflers off there was a good bit of water in the pipe.