Catalytic converter rust

I cant unbolt my catalytic converter because it is rusted to hell. Im trying to install my short shifter. Is their anything you can use besides wd 40 to get the nuts loose. I searched and cant find anything about it!! :gun2:

Try torching it. Or melting candle wax (apparently it works, I’ve never tried it). The last thing would be to just grind off the 2 screw bolts and replace them…that’s what I did.

Regards,

Oz