Pardeeboy

Hey guys, new to this forum and a new cherokee owner as well! So when I got my 2000 cherokee the guy said it had a manifold leak (no big deal) so I had bought a new gasket and to make a long story short the Engine is a 99' and the body is a 2000 with the stock manifolds. I had a hell of a time trying to figure out why it still leaked after I replaced the gasket. a lot of head scratching later I figure out that 2000 manifolds will not seal properly up to a 99 head. so I bought a 99 header and installed it today. Now, my question is; what am I supposed to do with the 4 O2 sensors? I took it down to muffler man today to get an exhaust put on it. he said he wouldnt put a cat on it if i didnt want. which i agreed to, but after reading some on here Im thinking I need to call and tell him to put a cat on. but what about those 02 sensors? should I have him weld in bungs? but where?

Thanks guys!