Some might wonder why using stock gauges are inefficient. The answer is really quite logical. Stock engine
gauges are meant for daily driving, and taking it very easy on the motor. But once you start pushing your motor to the limit every time you drive it, you are no looking for more accurate readings.

The reasoning behind the more accurate readings is to prevent destruction of your motor. If your oil pressure drops your engine will only turn the oil light on at a certain pressure. Its much better to see the exact PSI on a digital screen. Even stock tachometers are unreliable. They are off a few hundred RPMs in their readings. This is bad, esp if you are red lining, and its only reading 500 rpms below what your engine is actually doing. Instead of shifting at 7200 RPM's your motor is actually shifting at 7700 RPMs, which could mean total devastation. Sensor and gauges are also used for tuning as well. When you are tuning a car, you need precision instruments. You need to know exact engine temps, RPM speed, air to fuel ratio, and even exhaust gas temps. Some companies make it easy to do all this. They use something call a control box to act as the brain for all these sensors and also lets you know if something is wrong or off.
Remember that when you are spending big bucks on engines and transmission builds, that extra insurance means "Just having the right gauges".