I agree, you get what you pay for with an air/fuel gauge. They can be very useful especially if you are constantly modding your car or if you have it dialed in close to limits. I think that goes for all of us with forced induction. Until the fuel system upgrade from Gadget/URD was available, we've been running lean on 1 end, rich on the other and many people as a result have blown knock sensors. The big difference in the gauges is narrow band vs. wide band gauges. If you already have a narrow-band air/fuel gauge like those from AutoMeter, one way to make it better is like what I have. I've got the Bosch M-300 Wide-Band oxygen sensor from PLX Devices
http://www.plxdevices.com. This has a wide-band O2 sensor that mounts in the exhaust just like when a dyno tune is done. It sends the signal to a digital readout that is accuare to <0.1. From there, they have a wide-band to narrow-band converter so it can also be hooked up to AutoMeter narrow-band gauges. This will make the narrow-band gauge that you already have installed read like a wide-band. Again, this option is pretty expensive > $300. -JoeB