imho...
any gauge will work as long as YOU know where your "normal" operating range is. Gauges that are "full range"(270deg) is more prefered since you can see the variances easier. As long as you know what your baseline is, any deviation from that is where you need to pay close attention to. So...will a $30 gauge do the same as a $300 gauge? Only when the operator know his vehicle.
any gauge will work as long as YOU know where your "normal" operating range is. Gauges that are "full range"(270deg) is more prefered since you can see the variances easier. As long as you know what your baseline is, any deviation from that is where you need to pay close attention to. So...will a $30 gauge do the same as a $300 gauge? Only when the operator know his vehicle.