mel-
like you said, the heat is more concerntrated. The firewall hole is a poor example on how clean a plasma can cut. That hole is common with a operator having a turrets fit while lighting up his arc. if a guide was used to steady the torch, the cut would have looked like you took a pair metal shears to the firewall.
so, curiosity finally drives me to post, yet again. iffin yous got this nice little toy, why in in the hell didn't you burn you a custom fan clutch wrench and save two big ones?