Help with o2 housing removal/install

[Galant409VR$]

I just bought an o2 housing and was trying to get the old one off but it seams that if I put any more tq on the bolts they might break off? Any help ful tips that might help? Should I spray some pb plaser stuff on the bolts for a couple of days? Or should I run the car and get them up to temp?

Thanks
409/2000 GVR4