I have a set of Kooks Catted Long Tubes and I've noticed a "rattle" for lack of a better word underneath the car. I haven't put it on a lift to take a look but could this just be the heat shield underneath the car rattling from the cats? Or do I have a bad cat? I've heard that cats can rattle. Any ideas? Friggin annoying!!

 

How long have they been on the car? Bad cats happen occasionally... or they get blown out... but usually with S/C or nitrous high horse applications.

It's possible there could be something under there that needs to be tightened. If you bottomed out on anything, that would do it too.

CR

 

I put them on late last summer and I noticed a rattle right away but it seems worse now. I didn't drive it all winter and the pipes have probably been on for only 1000 km (600 miles).