Backfiring= antilag. Rally style antilag will have the thing backfiring like hell under deceleration as it retards the ignition timing and dumps fuel to literally explode in the exhaust manifold and turbine inlet to keep the turbo spinning for instant throttle response when the car goes WOT at the end of the turn. I'm not sure how they accomplished it in that car- it seemed a bit excessive, especially when he spun it out and it was sputtering horribly as he backed it up. It should only happen under hard decel, maybe they ghetto-rigged it somehow instead of doing it properly with an EMS?