Replaced the air filter tonight with a Wix, and while reassembling the 2 halves of the air box I didn’t think the back was sealing properly. Grabbed a small flashlight and looked carefully around the 4 back tabs, and sure enough, there was a small gap all along the back edge. The outer perimeter of the box halves are tight, but the inner “rim” that is supposed to seal along the filter was not tight. Solved it by zip-tying the upper and lower half TIGHT and that eliminated the gap. The zip ties can stay on permanently. For all I know, that gap has been there since new. Maybe, maybe not. Either way, check your air box seal by looking for a gap on top of the filter, thru those rear tabs.