Bought some soundcats for my duals about two months ago and now after a good hard drive they seem to have a sulfur type smell, almost hte rotten egg smell. When I first start the car and drive for a little while they seem to smell just fine, but after a long drive I get the rotten smell. I don't have the AIR hooked up, although these cats are not supossed to need it. I also ran the cats as close as possible to the header collectors, but the left side could only go so far cause of the support brace underneath, so they are about 10 inches from the longtube collectors, is this to far, I've seen other setups with them this far away, but never heard anyone complain. Could heavy heat from hard runs cause them to not work right, or is this smell expected a little bit.

 

that nasty smell could fit the description of an "gutted" or catless car to me. Possibly its just a temporary burn off of somekind of coating inside them. Also "flux" from a weldjob can start to smell when it heats up. Got any left over flux on your welds?

 

well thats interesting, I never thought of it being flux. I did the exhaust myself, so its not gutted and does smell different than my open cutouts, that I installed just ahead of the cats, its a heavy burning smell not exactly the rotten egg smell but close. I used a flux core mig to weld the stuff together, and its possible that some might have burnt through that got stuck inside, I definetly didn't clean off the welds on the inside, I guess I'll just have to wait and see what happens if it gets worse or not. I know I have only driven about 1200 miles since installing them, maybe less.

 

When i got my new exaust on it did that same thing for about 3 or 4 weeks, id get under the car and try to see if you can knock off any extra left over flux build up.