i agree crashby,flex is definately a tuning option.alot of it depends on the layout of the suspension components and weight distribution.if you cannot get the car to grip in low traction surfaces,flex will give you that needed traction.the bad thing is that it is not consistant.the car never flexes the same twice and will also fatigue the material.in alot of cases it is necesarry but i personally run my cars as rigid as i can.if i need felx i will use it but the rule is,the stiffer the faster as long as it stays on the track.
our chassis for the 1/12th was designed for carpet racing,but because of the placement of the suspension components,it opened a new window of adjustment that allowed it to work extremely well on asphalt.thats all i have to run on .and yes,it gets scratched like a mother but it is so fast.