Recently my Sol started making a sound similar to a heat shield vibrating, except varying in pitch. It seems to only occur once the engine is warmed up, and seems to come from directly underneath the cabin. I finally looked under there today, and I am sure what is going on is that the casing on the cat is somehow vibrating. When I hit the cat with a broom, it sounds just like it. The sound also seems to come from the cat. I don't really want to spend money on a new cat, and would rather look for a way to fix the current cat, or to put in a straight pipe. Here in Michigan we don't really have a problem with having no cat -- there are no inspections. What's a good price for "test pipe" labor? If I remember correctly, I know a place that does it for $30 or so (pipe included), but is almost 2 hours away. Is there some way that I could weld the outside of the cat, or epoxy it or something? Thanks for the info.