Spark plug querie

[Brenton]

Happy New year all, I have a 2stroke 15hp 2005 Mercury which I want to replace the spark plugs in. The existing ones are NGK BR7HS-10 and the service manual calls for a BP8HS-15, I was under the impression that the gap should match the hp? Which is correct?
Any advice would be greatly appreciated.
Thanks in advance.

 

[racerone]

Numbers on the sparkplug and the gap have nothing to do with the power of the motor.

 

[timguy]

Need serial number, then check this.