I have a 2004 xb12s that is pinging at 4000 rpm, once past 4000 rpm pinging is gone, I have an after market exhaust and k&n filter. This weekend I'm changing the spark plugs to oem (not sure if the ones in there are oem). Cleaning the air filter, replacing the fuel filter and checking the timing. I use nothing but 91 octane, harley synthetic oil.and I'm going to load the race map to the ecm and tps reset. Any thoughts as to if I should solve my problem? Is this just a mapping issue since it only happens at 4000 rpm?