[the skullcowboy]

C.E. Evans wrote:

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Nope. But from onscreen material alone, 24th-Century warp engines weren't any faster than those of the 23rd-Century (they were possibly even slower), but could enter transwarp at Warp 10. Otherwise, the warp scale appears to be unchanged between TOS and TNG...

Actually the warp scale was drastically changed between TOS and the TNG timeline as indicated by this chart

http://www.star-fleet.com/ed/warp-chart.html