The Stage V's for starters require machine work (porting), the victors are supposed to be good out of the box. Stage V was having a bad quality issue with the castings being badly pitted but they solved the issue.
My Stage V custom heads were sent out to me with the bad pitting (I have pics) and I sent them back and waited over a year to get new heads. The stage V's, according to Tim Banning, are supposed to be a much stronger material than the victors and my new heads
are very nice, all machine work done by FHO. Thankfully Eric at Stage V kept me updated as to their progress with solving the issue and was adamant that I get a quality product. Power wise, if the heads both breath the same volume than the power should be the same and yes, one
costs a lot more than the other.