It is power lost if oil and gas is escaping. I would also pose the question does the pipe get hotter with an air leak? It’s all about building as much pipe pressure as you can.
Something else I thought of while not working today and watching World finals from my desk. We tend to run these motors WAY leaner than what Rotax recommends in thier fancy charts in the operators manual. This would definately burn out the first 2″ of packing. I pretty much open and inspect after each race weekend.