The place I went are spesialist on rebuildind damaged mag and they also work for insurance compagnie. Not sure at what temperature they heat them but their work is waranty for 1 year and I have never heard that someone had problem with powder coat.
All I can say, they did a nice job and I like the result !
Many OEM wheel are powder coat.
"Mag" or magnesium wheels are not legal for use on America's highways. Yes, I realize your canuck so that regulation my not apply to you.
Here's the problem with "specialists" powdercoating wheels~
People that powdercoat everything/anything may heat the wheel to the point of annealing it. This softens the wheel and makes it prone to failure at a lower threshold of stress. They, in effect, may remove the temper of the wheel.
Luckily for them, there are NO REGULATIONS for wheel testing or strength (or anything else) in America. That means anyone can start making wheels and selling them. Anyone (including you or me.) It's pretty hard to believe that in this day and age, that there is anything that is not controlled by some form of Gov't, but, there it is. Maybe I should start a wheel company as I'd LOVE to have a business where the Gov't isn't in all of my pockets. (Maybe I should seriously look at this....)
I've already had a business that the gov't was severely "burdensom..."
Anyway, back to the wheels~
The only "quality" testing is done by the E. U. (TUV)
If it passes that testing, then you've got a decent wheel. Otherwise, you're just guessing at the quality.
Don't get me wrong, I like powdercoating, but temperature regulation is CRITICAL for wheels.
Check with Speedline or Alcoa or others and see what they say about powdercoating their wheels...