Will I harm my engine by using a magneto?
Absolutely Not. No matter which Don Zig magneto you choose to buy for your engine, no matter how high the amperage rating of that magneto is, the fact that the ignition is now supplied by a magneto will not harm your engine in any way.
Magnetos do not cause your engine to run hot, lean out or burn up parts. Magnetos are in fact the most consistent, durable and reliable ignition system ever devised for the internal combustion engine.
Consider this fact for a moment. Every conventional piston engine aircraft that you have ever seen flying, in your entire life, no matter who manufactured the aircraft or the engine, no matter where you were at the time, had a magneto ignition.
Out of all the possibilities for ignition systems available to them, no engineer has ever used any other type of ignition system on a piston engine airplane. Would they do that if magnetos caused premature failure of engine parts or weren't the most reliable and powerful ignition system available?
No ignition system makes a more powerful [higher amperage, longer lasting] spark than a magneto and the faster you spin them the more powerful the spark becomes. This characteristic does not harm your engine; it makes it more powerful and reliable.
If you have seen magneto-equipped engines that have had engine failures, it was do to the fuel air mixture or the ignition timing be incorrectly adjusted or to various engine components being stressed beyond their performance limits, not because the spark that set off the combustion process was "too hot".