You really don't need to bother switching the props and testing that way. The Mirage and Mirage plus are diffrent propellors and you would see an Rpm diffrence between them. what you should do is contact your local Merc deale who should offer a loner prop program and play around until you find the right combo. But there deffenitly is a differnce bettween your props it was more than a diffrent name.

Hillbilly - I think they are different also, thanks for the advice.

You most likely did this already but put both throttles about 3/4 open and check to see if you Throttle body is open exactly the same on both. Could be a small cable adjustment would add to the prop difference

There indeed is a difference between the Mirage and the Mirage Plus. The Mirage Plus has a larger blade surface area allowing for additional cup. Typically the RPM Difference is about 200 at WOT. So there is still 200 unaccounted for. Now if the propellers have ever been worked then this could make the difference as well.

Julie

What kind of top speed are you seeing with that boat? I have looked at a couple with 500HPs and wonder what the top will be. Thanks

Top speed is 67 MPH.

Don

Don't always treat your tach readings as the gospel truth either.

The Stewart-Warner tachs in my friends 1989 Bullet have not told the truth in years.

The Mirage Plus is more efficient and will cause less RPM.

I would do a compression test just to establish that the internals are healthy.

Which motor is your power steering pump on? I don't think that it would be 200 rpm, but it has to be something.

I never considered the power steering pump - it does happen to be on the engine that seems to run slower (the side with the Mirage Plus, not the standard Mirage). I don't think the power steering pump should have much of an effect.

The Tachs were updated within the last 5 years, but they could be off.

do the motors sound in sync? When you get them sync'd they will make a steady sound ,,,when off a litttle, a long wave and as you differ the engines more the "wave" will go faster. You'll hear it after playing around a little then you'll know for sure if your tachs are correct in relation to each other.