I am doing the same thing as you. I have been driving 4wd buggy for the last three years. This is a totally different deal. I am starting out in stock 17.5 buggy and I feel it is more than enough for starting out. I have the tekin 17.5/rs combo and with the boost it is close to mod speeds. If I was running mod and had a boosting type esc I would run a 13.5. I am at a small indoor track. I don't use any drag brake in 4wd but its useful in 2wd. The biggest change is entering and braking in corners. You almost do the opposite of what you do in 4wd.