I am in the process of removing the floor pans from my 69 mustang. The firewall extension pans are fairly badly pitted and I need to cut the out. My question is what is the best way to remove this section without damaging the panel below (torque box?) or should I just replace that as well :confused. I used a 4.5 inch angle grinder with a cut-off blade for the rest of the rusted out sections and this worked pretty well. Any suggestions would be greatly appreciated.