Stock is 17/57. 19/55 is higher top speed, less bottom end, 16/58 is high torque ,less top end. 18/56 is the middle . I'd stay with stock for now with your stock motorwell I ordered some taller tires 7.5" vs 6" tall and my gearing is WAYYYY Tall now lol, so I ordered a gear set 16/58, 3.625:1 coming from ??? I think 19/56 , 2.95:1 ? not sure what the stock gears are on a Rovan Buggy ? If so it is a perfect % change os 20% on both. check my math for me.