RE: 99+ Amps drawn by my Hacker C50-14XL
Magnets de-magnetise when they get too hot. Basically the stronger the magnet, the lower the temperature at which point this will happen. As far as I know, scorpion is the only manufacturer that uses magnets that can withstand high temperatures. Overall any RC electric engine shouldn't get much hotter than the mentioned 160 degrees, wich is already on the hot side. Most used magnets will start to de-magnetise around 185 degrees, and keep in mind that if you measure 160 degrees on the outside, the magnets might be even hotter than that.
You can imagine that if one would replace the default magnets on an engine by magnets that have 'halve the strength', then the current will go up. This is since your ESC will still want to try to spin the prop at the same RPM, so it will just pump more power into it.
Having a good airflow over your engine is pinnacle in this, but it's useless to make all kinds of tunnels if your exhausts aren't functioning or not big enough. Roughly you should have at least 1.5 (preferabely more) the exhaust-opening vs the intake opening.