I'm afraid I wasn't clear. The Apollo has a top speed, but during missions where there are no shields, this top speed is higher (as a result of no shield energy).
For however many years I've played the game, this top speed has been 65. Now when shields are disabled, this speed goes up to 66. Similarly, every other fighter's "no shields top speed" is 1 m/s higher than it would be with a retail .exe. I'm no coder, but I was speculating that it may have had something to do with somebody going in and optimizing some code, resulting in the computer rounding something differently.