C90 Spark Plugs
 

11,000 miles... about time to change the spark plugs in my 2007 C90.
The parts manual shows 6 options. Three numbers for two brands. Does anyone have a spark plug recommendation for a bike running in the central U.S. at 100 - 400 feet asl burning 89 octane (or above) unleaded +\- 10% ethanol