I have a zxi 1100 the PO put a 900 in. I had sent the impeller to impros to have a little pitch taken out to compensate for the smaller engine.

At WOT my zxi is turning 7400 (on the factory tach).

I thought it was good but the app on my phone said I was only going 43 MPH. An 1100 should do over 55 and a 900 should be over 50.

I assume the pitch needs to increase but wouldnt that decrease my rpm. I think it's pretty close to where it should be.

Any idea what adding a degree or two would do to the max rpm and speed?