Originally Posted by eComet

Try to add 10g weight under each of the front arms and apply some Tamiya anti-wear grease on the front steering shafts to reduce the bouncing.

Did you use the damper plate on carpet? Try to use thicker grease or tighten the plate, which will reduce the tire lift. Only try to tighten the diff when you cannot get enough steering. I tried this at TQ, a tight diff will give you A LOT more steering but the rear will snap oversteer exiting the corner.