i just purchased a 2007 28 eliminator daytona with speedmaster lowers. i believe they are mercury but not sure. they are grey. my question is this is my first boat with speedmaster lowers what is the advantage and what is the disatvantage of haveing speedmaster lower units?

they are either mercd speedmasters, imco's more than likely. the imcos have a very short skeg where as the merc units have a very large wide skeg.
the advantage is speed. the disadvantage most commonly is water pressure. if not set up properly you can have very high water pressure which can be less tahn good for the engine.
more than likely if it came this way from the factory its on the money. if not the only way to tell is by looking at the setup of the water system and actual driving at speeds to see pressures and handling characteristics.

good luck.

So What U Are Saying The Faster You Go Your Water Preasure Should Increase Or Stay The Same. . I Assume As Long As It Doesnt Drop In Preasure When You Start To Run Hard I Should Be Ok. Thanks For All Your Help

Its probably a Merc Sportmaster. Post up a pic and lets check it out.