Probably so little sensitivity that you won't see the needle budge.
I ran the underhood bypass, but w/ a shunt diode that builds up enough voltage drop to move the needle (~0.75 V for 3/4 scale). Unlike a simple resistor, as current increases beyond 30 A, the voltage drop barely increases. See my post "Modernized Engine Wiring ...". But unless you understand physics, you will likely make a mess in fooling with such high currents.
