Roger.. they act more like shock absorbers with a broader range of frequencies over which they can operate.
Again.... if you are in the NHRA Top Fuel league, you would engineer for this weight. For us 'mere mortal' racers and gearheads, the energy absorbed in this size and weigh of mass is truly trivial.
Seriously, it is in the range of maybe 1 HP for an 11 second car; you can tune the ignition timing a couple of degrees, or have the track temp drop a degree or 2, and more than get this back.
