The Tachometer Readings forum has a thread on Saito 72 performance reported by readers. A quick look shows almost everyone is using a lighter load prop than a 14x6 on the 72. The one guy reporting on the 14x6 was getting 9000 rpm - which is below the rpm for best power with that engine. THe 13x6 reports run 10000 to 11000 rpm. I run 13x6 and 14x4 props on my YS 63 at 11,000rpm. I am sure the 14x6 would be too much load for it . If you use a lower load prop and let the engine rev up to where it produces its best power you may be happier with it.