Is an O2 sensor necessary for my 1500cc gy6?

[Nemesis8]

Hi guys. I'm new to the forum and somewhat new to the world of scooters. I've owned my 150cc Jonway for about 3 years now, but I'm just starting to make upgrades and mods to it. So I bought a new performance exhaust for my bike and when I went to check it against my current exhaust I noticed something coming off of the current pipe that my new pipe doesn't have. I'm guessing it's an O2 sensor. If I install the new pipe without an O2 sensor will it cause me problems? Or should I just leave the old pipe on with the sensor and install just the new muffler? The new pipe looks really nice, but I could easily remove the rust from the old pipe and paint it with high heat paint. It just won't be chrome like the new one, which is ok with me. I'll also be installing an oil catch can at the same time right above the muffler. Anything I should know about the installation that isn't obvious? It seems pretty straight forward.