Ok my boat tops out at 5000 rpm's (assuming the tach is correct) and runs 50.3 by GPS. It has a 3 blade stainless prop that has S22 stamped on it. Other than being a smokey old two stroke it runs fine and seams to plane out decently enough, about 4-5 seconds. Does this sound right for my boat. Motor is a 1983 Mercury 150 (Mercury dealer said it was an XR2 by serial number???) on a 1986 ranger 372V hull.