I just bought an 18' Sea Pro 180 CC and I had the choice of a 2 stroke Yamaha or Johnson (90 hp). The sales rep said they are both great motors and that the Johny was 4 cylinders and Yamaha was 3. I chose the Yamaha just because that is what I see charter fisherman using in the Chesapeake. <br /><br />What are specific advantages/disadvantages of both?<br /><br />Also, 4 stroke is not an option given my budget...Got the boat w/trailer out the door for $15,400.