here's what i'm seeing with my ultimate inferno: i can play the same line with the ultimate inferno and the classic zone----same ball speed, same release, etc. the classic zone is carrying where the ultimate inferno is leaving ringing 10's and swishing 7's. granted, the cover prep is different on both balls( ultimate-wetsanded 1,000 grit, classic-wetsanded 2,000 grit and polished ). i believe the ultimate is burning up a little energy going down the lane and the angle of entry for each ball is different.