I have a Kenner 21vx with a Etec 200HO. I get 54 mph at 5200 rpm with a viper 14 3/4 inch prop with 21 pitch. Is this normal for this type of boat or can it be improved by different prop selection. I am clueless? I am also satified with the performance but have the option to trade for another prop with the dealer if I decide I would like to try another one.