pros = a more free flowing exhaust.

cons = going to be a bit louder and you'll be killing baby seals (Ask Gore)

if you're just going to straight pipe the cat, then you shouldn't get too much of an increase in volume. If you are going to straight pipe from the down pipe back, then you're going to be stupid loud and we'll all hate you.

You might get a CEL depending on how your emissions is set up.

do some research on what makes for a good exhaust system.
ignore all of that crap about needing back pressure and all of that. That's just bullshit from someone that doesn't really know what they are talking about.

And the only reasons you would loose power is if A) your ecu is set up to read the emissions levels (ie- obd2) and compensates for it by adjusting the fuel and or spark. OR B) you set your exhaust up wrong like a majority of people do and probably have way too big of a pipe on which can hurt performance more than too small of a pipe. OR C) you didn't get on the dyno right before you put your exhaust on so you don't really know what your car was putting down so based off of the internet says your car "should" put down stock, you lost some power when in fact, you probably gained a couple, or at the very least, broke even because you were putting down far less power than you think you were.