Just had my smog done. 457 ppm on the "NO" portion with a max allowed of 467 @ 15 mph. Although I passed I'm still concerned next time I may not, as well as any performance issues that may come up. Called around and the dealer most likely says its the cat. but can't really tell with out me shelling out money for them to look at it. I have a 99 LS with around 95K on it. I last got the 90k service around 88 or 89k. Any thoughts would help.