I have a 1987 120 evinrude that runs perfectly. Noticed the rpm's at wot were around 4900 with a 13.2x19 aluminum prop. Installed a new 13 7/8x17 viper ss. Now at wot its 5900. I'm satisfied with the performance but need to know if that's to high. Can't find the rpm range anywhere. I have been told it depends on which power pack you have, so how do you know? Thanks for any help.