Why did Dragon Ball Z Kai change "It's over 9000!" in the TV version to "It's over 8000!" in the DVD version?
Quoting wikipedia

In the original Japanese and English-translated mangas as well as the original Japanese anime series, Goku's power level is actually read as &quot;over 8000!&quot; (8000以上だ…! Hassen ijō da…!).&quot;
In most versions of the scene dubbed in other languages, Vegeta actually says &quot;It's over 8000!&quot;. However, even in the Remastered Uncut Funimation English dub, Vegeta still says &quot;It's over 9000!&quot;, now performed by Christopher Sabat. This change was made due to inconsistencies with the dubbing process; the production team claimed that &quot;9000&quot; fit the mouth flaps of the animation better.

So it's originally 8000, but it was dubbed as 9000 to fit the mouth flaps.