Which prop ? Zuke DF250 on a Sceptre

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Im running a suzuki 3x16x18.5 prop and im only getting 5450 rpm wot with light load and engine trimmed up.Recommended rpms is 5500 to 6100.My cav plate is about 1/2" above the keel.
I have a full canvas enclosure and bottom paint ,motor mounted on transom.I heard that Suzuki props are usually a higher pitch than what is stamped on them.
Thinking I should go to a 16x17 and raise the engine one hole.

If anyone is running the same set up I would love to see your numbers and what prop your using.
Thanks in advance