Actually yes, the first tank this year had a half can of Sea Foam in it. That may explain the front plug. The more I look at the rear one, it is more brown than I thought. I plugged the short, large diameter hose that is between the AIS filter and the AIS box under the tool storage. It seemed to help a little, but I still think the exhaust is popping too much and more than I remember last year. Since plugging the AIS, it doesn't have the little pops at idle like before.
No other work besides the slip ons.