Rattling...
Something under my car/on the motor (I couldn't tell at first) started to rattle a little while back and has seemed to get worse over time. All my heatshields seemed to be tight when I checked. After knocking the cat a couple times, I've realized that's where the rattling is coming from. Has anyone else had a catalytic converter go bad? It isn't the heatshield...it seems to be the cat itself. Also, I might as well upgrade to a high-flow cat if it's worth it...anyone been able to tell a difference between stock and a high-flow cat?