Apparently you can get some pods to run right if they have an internal velocity stack. i.e, they have a rubber tube inside the filter itself. Those cheap hipster special conical bird strainers are not the ones. You need some vacuum generation before the throttle plate to get the slides to open properly. With no/low restriction, the diaphragm will not get the signal strength required to reliably lift the slide and needle. This is one reason many jet kits require drilling the signal hole in the slide. I remember the giant hole in the powerband I got when I removed the lid off the airbox on my GS1100.