Re: Increase Power
^Right; with Tohatsu/Nissan (4-stroke anyway) 8hp and 9.8hp are the same engine but with different carb (I think prop also) setups. The 15hp and 20hp are the same way. The 25hp and 30hp are the same way etc... but If it's 2 stroke I'm not sure about the Nissan/Tohatsu... 9.9-15 evinrude/johnson 2 strokes are like that but I'm not sure about the newer Japanese ones. Most people talk about vamping up their johnnyrudes so that may have been where you heard about it.
