Running an open catalytic converter?

Hey guys.. Haven't posted anything in a bit, so I have another question to keep you busy haha... Being a teen (16), I want to have my car to sound louder and better.. I really want to run an ets open downpipe, but that money isn't gonna Be coming anytime soon.. So, how would the car sound if I ran the stock exhaust, but resonator and muffler delete? Basically the last part of the exhaust is the cat converter. Where I live, sound isn't much of an issue. Also, if I get a tune, any ideas on hp gain? Thanks everyone!