1992 4.3 MERCRUISER 1.85GR and a 14 x 21 prop. 256 hours on the motor and it sounds good. Motor sounds great but it seems like it should have more. I'm only seeing a 3800 RPM output at 35 MPH WOT. I'm going to verify the RPM with a tach to make sure I'm reading right. Speedo I'm assuming it...