Just purchased a 2015 RT 178 Ranger w/ 70 four stroke. It has a Solas 3441-138-13. I assume 13 pitch. Never had this small of a motor before. Took it out for the first time and it hit 7000 rpm's pretty quick. With two people it got out of the hole way faster than I thought it would. Found a chart that said max is 4500 - 5500. Is this true? If the tach is correct what pitch would be good?