Originally Posted by Dackelone
Why even bother to take your car in? Why not just change or pay for an oil change. Why risk a dealer visit? I would just change the oil myself.
The technicians will know in about 1 second if your car is catless just by starting it up... they have ears and noses and a lot of experience. Just because it doesn't throw a code or a CEL doesn't hide the fact that your car is louder and puts out a gas smell.
That being said, if you are just going for an Oil change and no warranty work is required, they may not care. My dealer was cool with my intercooler, mid pipes and charge pipe for all services before I had to get a low pressure fuel pump sensor changed. The sensor has zero to do with the mods, but he wanted them off before he could do the work.