No, I have not tried that yet, but I have found that most of my side port diesels will experience a 2/3rds reduction of their racket by covering either one of their exhaust ports. Some do speed up a little, others maintain the same RPM.

A friend of mine told me that one day when running his Burford Deezil, he blew air from a nozzle toward an exhaust port. He said the engine revved up about another thousand RPM!