Okay, well. I am giving my hdc315's 2k each daily, have 2, so a total of 4k wrms daily; they're copper. I know people who have given the coppers 3k wrms daily. Now, i also know people with correct electrical, box, etc.. 4k wrms to 1 18" alum. coil hdc3. I mean, i have heard from multiple people that coppers handle power just as well as the alums. but i honestly couldnt tell you. i run the coppers on 2k wrms each, and they rarely get warm...