I never measured it but the car felt stronger above 4000 rpms and gas mileage went up about 10% for both city and highway driving. Hope that helps a little.
P.S. One thing to note. You MUST use plain old copper spark plugs with a slightly wider gap; any thing else is a waste of money and is counter-productive to the high energy coil, especially fine wire electrodes which were originally designed to make up for an aging (weakening) ignition system. If I could find some surface gap style plugs(a.k.a. oil-burning plugs) to fit I'd use them.
[Edited by intruder on 02-18-2001 at 11:09 PM]