Not many people are using 25T in my home track. One of the problem, I feel the 25T pulley is too close to manifold hanger.
In 2007, I change my racing strategy to start with 0.955 - 0.945 underdrive ratio ( RWD ), so later at the end of race ( 30 min or 45 min ) I can end up with 0.999 ratio ( 4WD ). I feel better driving slightly 2WD. I also use 20T brake pulley to soften the punch and increase 1st gear top speed.