I just read all the related threads to this post, and the post itself. Some have very negative remarks, but even after all the negative remarks, they didn't say they took them back out and put the steel ones back in. Also, I used ceramic in my diff when running oval. I found that I had to rebuild the diff every run with steel balls in the Diff, but with the ceramics, I never once had to rebuild. I just put a set of ACER's in my mtx4 for a major upcoming race. If I can pick up less resistance and go faster with less power, or should I say drivetrain drag. If this results in being able to let off the throttle and let the car roll at the same speed for a longer distance, then the advantage will be apparent in fuel economy, as little as 2 seconds has been the differece of finnishing a qualifier and picking up an extra lap. Fuel econonmy is the only thing I am looking to truthfully gain.
As for the weight advantage, the full set I put in, I saved less than 3grams of weight, but I added 70grams to the car to make it heavier, and I removed 50grams to lighten it on the topside.
Anyway, I have already noticed that the driveline feels more "free" than with the steel bearings I had in it. Only time will tell as to what I feel on the track, in a month I will know for myself.
Am I going back racing?...Hmmm.. Not anytime soon... But soon enough.