RE: ok to remove catalytic converter
Three inch pipe is some pretty serious piping. You want to be careful though, b/c eliminating too much back pressure can rob you of low end power. Many folks before you have removed them, and if sound or weight reduction is your cause, then you will probably accomplish something.
But again, unless you are going to run 600hp, or spend alot of time above 4k rpm my bet is the difference will be neglible performencewise.
BTW, there are "test modules" that can be purchased to fool the computer into thinking it is always seeing the proper signal, so that is not a big deal if you decide to lighten the load.