I spend all day today trying to solve my acceleration rattle problems and I think I may have found the general "area" from which this noise originates from. My roush exhaust is fine, passed the "smack" test. From there I went up to the cats and started hitting (lol) things. The passenger side cat is solid, no rattles, no movement, all is peachy. However, when I hit the driver side cat I could hear a very quiet version of the rattle I hear during acceleration. Which/where/what bolts do I need to crank down on to eliminate this problematic rattle?? Thanks!!

 

I seem to recall reading a TSB re: the heat shields on the cats causing the rattle...

 

I don't think it's the shield, as I was holding the cat and hitting the shield and couldnt make the noise. However, if I just hit the cat while holding the shield I heard the noise. The shield is tight and wont move even with me cranking on it with my big mitts lol. My truck also has developed a rough idle and an odd exhaust "pressure" when slowing down.

 

Clogged cat, time for a set of hi-flows.