Here is the article BradH referred to: ( Thanks!)

http://www.hotrod.com/articles/light-vs-heavy-wheels-comparison/

With the fronts jacked up off the ground you can visualize taking something like an electric motor attached to the hub and accelerating each wheel to simulate top end speed rpm in roughly10.8 seconds taking a lot less energy amps/Kw//Hp than the massively heavy 4x4 wheels that were on it. I guess the et fronts are also about 2" taller so they'll spin a little slower too over the course of a run. 60 pounds is a little more than 2% reduction so roughly like 80 on a 4000 car.

My guess is around .15 seconds so probably worth it. Had to drastically cut down the hub register and redrill the bolt pattern to get the fronts to fit.

Time will tell tho...i tell you at least its easier to push around the garage, lol