I like the 2.25mm chassis, feels best for me
Enough Traction and more on-power steering :P ... but 2,5mm is fast, too - especially on carpet.
Topdeck i tried already 2.0mm flex, 2.0mm stock and 2.5mm optional.
2.5mm optional was very bad, don't like this - on ultra high-grip carpet it have a small amount more cornering speed, but the car grip rolled a lot faster ...
2.0mm stock should be the best all-around solution. 2.0mm flex was very good for me on my local track, much more steering but a litte bit more nervous rear end. As a lot of you know already, i have the same "nervous" driving style like Marc and we both "prefer" the 2,0mm flex topdeck.
One page earlier i already showed a picture of my car...