Whether you have a normally aspirated or forced induction engine, any serious engine modifications will require the use of an Air/Fuel ratio gauge to warn you if the mixture is too lean or too rich.

Auto Meter's 2"electrical A/F ratio gauge uses 20 small LEDs arranged in a sweeping pattern to indicate "lean,""stoichiometric,"and "rich."  Although the Auto Meter gauge is not as accurate as a wide band Lambda sensor,...

Installing an oil pressure gauge in your car is cheap insurance against costly engine repairs, as long as you remember to monitor the gauge regularly while driving your vehicle. A failing oil pump, loose oil filter or external oil lines, or oil starvation from hard cornering can all lead to dangerously low oil pressure. 

VDO's oil pressure gauge reads from 0 to 150psi and is backlit for night driving.  Gauge is...

If you have a turbocharged or supercharged engine, a boost gauge is critical for monitoring your forced induction system.

The VDO boost gauge measures from 30 in/Hg manifold vacuum all the way up to 25psi of boost.  Gauge is 2-16"diameter and backlit for night time operation.