removing sensors on the tail pipe

Oxygen sensors?

Most of the time with the proper tool, factory installed oxygen sensors break loose with little difficulty, since the factory uses the proper anti-seize compound on them. Sometimes they can be a bit stiff to thread out because stuff has built up on the threads, but they generally come out. It's when some backyard bozo replaced them already and cheaped-out by not using the proper anti-seize, that you may run across difficulty.

Some replacement oxygen sensors come with a small package of anti-seize compound in the box. Some dishonest auto parts store clerks steal them. Check before you leave the store.

HEY! I resemble that remark!!!

Actually, why steal a little tiny packet, when they usually ship a dozen spares in the box, and a whole tube of the stuff costs a buck with the employee discount?

But, I suppose people will take anything...