Whats considered a "good" air fuel ratio?

http://www.overboost.com/obs/browse_subcat.asp?cat_id=10&cat_name=Gauges+and+Pods&sc_id=46&sc_name=Air%2FFuel

Most people get the AutoMeter A/F ratio gauges.

I would say for a normal motor best hp is somewhere around 13:0 - 13:3 to 1.

With a forced induced motor to help keep combustion chamber temp down and to help prevent detonation anywhere from 12:0-12:3.

If you have water injection you can pull out some fuel and tune close to 12:5-12:7 to 1 for max power.