The real secret is to pick up 2 or 3 bodies, as it is the quickest tuning aid (ie less then 10 seconds to change the body) and it makes an unbelievable difference in handling. It will take a couple of laps to adjust to the difference in the body. Like JRS_chris suggests maybe the R9 gives you a ton of front bit that you need in the rain to make your standard setup just work.

-b