Same here. I can't say for sure that it made any real power difference, but the sound difference is without a doubt cool enough that the top filter is well worth the cost.
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I am actually running a real K&N because the others just rot with the Uk weather .i tried removing the front rubber and it seams to reduce the low down torque on mine I have actually considered removing it and replace it with a custom more cone shaped ones to create a more ram air effect .
Your assessment about losing a bit of torque contradicts What Lloydz showed me on the Dyno when I got my Vision done. If that is your finding than using that as a guide you shouldn't do anything else.? you get no advantage then by thinking about the AIS and top filter. Any change requires another adjustment to optimize it as much as possible.