Balls!

For those using a fixed chassis (simlab, etc,) if you place 2 hard rubber balls under the front feet, you get a very nice (but subtle) chassis movement over bumps and rumble strips etc, if you run 5 or more NM of torque through the wheelbase. Hard rubber is best. My lard arse crushed the rear 2 which were standard soft bouncy balls. It's no motion rig but it does add to our beloved "imershen".