Not sure on the 2005's. URD sells a O2 sensor elim kit that works like a charm on my 2000. When installed the truck does not throw a check engine light. With an aftermarket exhaust the difference in sound is like night and day, its loud but not obnoxious it can be controlled. I did it because I was having too many problems that I thought the cat might have been causing, and once I removed it, a lot of the bogging down, hesitation problems that I was having went away. I don't condone it, but it fixed my problem. I don't have to worry about passing through any other states which is practically impossible or smog checks. It's not for everyone I would say get a test pipe made so it can be switched in and out, and only remove it when you're taking it down to the track or what not. Then again, I think the sensor problem needs to be rectified unless you want a check engine light and the possible detrimental effects that comes with it. Thats just my opinion, take it for what its worth, I won't give an opinion unless I've tried it.