The 03 F7 was the fastest, out of the crate sled in 03! The chain case was still helping that! When they went to the Diamond drive in 04, a lot of people noticed right away, they were slower. Not much slower, but enough to notice! I was working at a Cat dealership by late 03, early 04, and that was a complaint for many 04 F7 owners! Their new 04 was being beat by their friends 03.