I been told at W.O.T. max rpm's should be 5050 -5100 rpm's.
My vyper rpms max out at 4800 rpms all trimed out, tabs up,running 28 piched labed, last guy had my boat said he would run 5000 rpms I never seen that 1/2 tank 3/4 tank, 2 people, 4 people. 74-75 mph all I see at 4800 rpms.Is it me or is that all the vypers run? I also been told from the last guy had my boat he ran 78mph @ 5000 rpm's. Can anyone help me out withn this? What can I do to have max rpms and run 78-80 mph?

Specified WOT rpm range is 4600-5000.

Try a 26P to see what happens. Not sure if there is much left if the prop was already labbed. What was the difference in temp and altitude from where the previous owner boated and you?