Gauges

A lot of these gauges are from omorimeter.com. I've never ordered from them, but people I have talked to are very happy with their products. I also will have some gauges from HKS and AutoMeter.

Mechanical Gauges needed the physical contact with the medium they are measuring, by routing a braided stainless steel teflon hose or a copper pipe from the area to the measured, through the engine firewall, into the cockpit directly to the back of the gauge.

Electrical Gauges differ from mechanical ones in that they use an electrical signal from the engine to the gauge. They measure capacities by relaying a signal from an embedded sensor at the source, to the gauge itself by a series of wires.

Some pros and cons of mechanical vs. electrical gauges

Mechanical gauges are cheaper.
Mechanical gauges are just as accurate as electrical gauges.
Mechanical gauges are much easier to troubleshoot than electrical ones.

Electrical gauges are more expensive than mechanical gauges.
Electrical gauges sometimes have a 'replay' or 'recall' function. You could see your boost after your last track run for example.