i used the car all of last season with no mods at all except for the added lead weights.
I have however started running the idler gear and will be getting the rudebits weights just to sexy the car up even more!! I would suggest having the front wing kit and extra droop front towers to aid tuning.
Compared to the b4 i found the car very easy and forgiving to drive, as my results proved. very happy with the cr2
