My understanding of chassis flex is to have the right balance of flex vs suspension movement. If the chassis stops flexing before the suspension compresses to its maximum travel on a turn, you end up with a darty car. If the chassis keeps flexing too much, you have a lazy car. When you have the right stiffness, the car just becomes so much easier to drive imo.

I'm sure the softer samix chassis for the 418 will benefit all types of asphalt conditions in different classes. The stocker is simply too stiff. For carpet, I would try out the front steering brace included in the samix conversion. As far as the build goes, the chassis holes are perfect and everything went together fine.