Will that be allowed in any multi-person-near-each-other track day? Exhaust that pushes must be very dangerous to be behind if you’re drafting and waiting for the next passing lane.
Unfortunately, he had the silly thing in reverse. It launched backwards maybe a hundred feet. The drivers reflexes to shut off the engine were outstanding. If it had gone much further, it would have climbed up one of the full grandstands.
I never stand behind a drag car with the engine running, or in front, or in the plane of rotation of the engine. (I've seen a few engine blowups, and parts often go out sideways.)