Small Engines (Lawn Mowers, etc.): Improving the HP of Nissan 8hp outboard, increase hp, restrictor plate

Question
I'm trying to improve the performance of my 8 hp Nissan (NS8B) outboard. I've been told removing a restictor plate can help the engine perform like a 15 hp outboard. If this is true, need to know how to do it. Once it is removed will the engine require tuning. The engine runs great and starts every time. Just would like a bit mor HP.

Answer
If it has a restrictor plate, it will either be right under the powerhead or it may be a different exhaust tube running down the shaft housing of motor.  If there is a restrictor plate and you remove it, your jetting will change (richer).  Just be sure to follow your plug colours.  However, I doubt that an 88% increase HP can be accomplished by removing a restrictor plate and jetting to compensate...that is an old wive's tale.  A restrictor plate might make the difference  between 8hp and a 9.9hp but that would be about it.  You could  gain better performance by switching props for your application.  Hope this helps.