[RedHawk47]

I believe that there have been posts that state that when they put a 13t on their RX3 that they got a higher top speed (which is counter intuitive).

This can happen because the RX3's relatively low power vs. the air resistance/drag does not allow max rpm before the drag exceeds the power available. By replacing the 14t with a 13t the engine is higher on the power curve when it reaches the 14t max speed and can go a few more mph before maxing out.