Not to be rude but i dun believe you 
vape 500w.  100 watts is hellish hot, 120w whoa am not wanna do that again,  150w I am never ever doing that ever again..
500w comeon  that is ludicrous
 
 
Meh perhaps I am wrong and you use suitable gauge coil but fog machines that fog whole stages are only 200-400watts..

 Holy cow thats beyond hot lol
Just adding an opinion,  you can get a 300 watt regulator that will give an honest 300+ watts they are not little but not so big..
http://apps.geindustrial.com/publibrary/checkout/NSR060A0X?TNR=Data Sheets|NSR060A0X|generic
As with almost all regs you can overdrive this one at 180% before it goes into protection mode so it will give ya 600 watts 120A easy..  I overdrive my smaller 10A 
mod 20%-50% everyday no issues almost 3yrs service..
Someone has wired one up in this section if it interests you...
When I do dial up to 100w+ I blow 
through the atomizer fogging my whole area.  Really cool effects with light shows..  Its still hella hawt.  lol