from your other post it appears to be a manual steer car.....while increased caster will improve high speed stability.....it also makes turning at slow speeds more difficult.
True, but I don't think the additional effort is very noticeable, compared to the effect of adding wide tires in the first place. For comparison, I have 3.5ยบ positive caster and 215/70-14 tires, with standard-ratio manual steering.