If you are only planning on running Solo courses you will be better off leaving a single cam in the car. If you want to cage the car and run on a track then I'd say B-series. If you are going to be that serious you would be cornerweighting the car and the extra weight up front would not make much difference, but the extra power would be better for the larger courses. If you watch a SCCA Solo event, you will notice that most of the best Hondas have Stock D-Series motors with minimal upgrades and really nice suspensions.