1992 Cadillac Deville Still Cutting Off Catalytic Converter On Deville

Ok so I am still cutting off my catalytic converter on my 1992 Cadillac Deville. I finally bought a diamond cutting wheel and it cuts like magic. My two questions are when I finally get the catalytic convert cut off in the back. It should just slide out right. I cut the back off first. My dad said he has never had luck with any catalytic converters. He said it is almost like it is welded in their. So he usually cuts both sides. He said he has tried wd40 and it does nothing. My next question is when I finally cut the converter out completely can I start the car. My dad said I could but only for a short time. He said I would burn the valves up. I want to start it to see what it sounds like then I want to floor it just to see how loud it gets. Thanks.