[mr0077]

If it pings on light throttle, guess what, you don't have it set up right. The motor needs more advance at light cruise than at full throttle at a given RPM to burn the mix efficiently. Opening the throttle even slightly causes the vacuum to drop, and a properly set up vac advance will take out ALL the vac advance when the throttle is opened...when you get away from station wagon cams and ignition curves and into aftermarket stuff, you may want or need an adjustable vacuum pot, both for rate that timing is added or deleted and amount of timing added in, to tailor it to your particular motor. They come with instructions to set up the pot to your particular needs.
I guess we'll have to agree to disagree...I agree with Myles on this one.