Ok my parts has arrived and I checked the exhaust hole. It is BIG. Much bigger (at least 5 times) than the 10mm orifice I have in the old ones.
After I cleaned up the old elbow, my rpm increased from 3000 to 3200rpm.
Now after I've antifoul the hull and cleaned up the prop & shaft, I can get 3400rpm. Sooo..., if I put in this new Mixing Elbow, I hope to get at least 3600rpm !!
2002 Hunter 326, SV Millennium 2
1999 Macgregor 26X, SV Millennium