Thanks everyone for the input, and thanks 440Jim for the measurements. I measured the top of my aircleaner last night and found just over 1/2" clearance with a play-dough test. According to the dimensions of both intakes, there is a height difference of 1 1/8". I'm running a drop base aircleaner and short 2 1/2" element as it is, so looks like I'm sticking with my M1 for now.