It makes more sense to enlarge the opening at the top of the stock airbox/filter retainer using a file, rasp or knife.
My K&N seals up snugly, you may have something out of whack.
My Rocket 3 sucks a ****** of a lot more air than my Speedy and the R3 stock airbox (with the same top opening as a stock Speedy) lets in plenty of air for TOR's, a remap and a K&N filter. The R3 smokes about anything out there 0-60 MPH if you do not mind replacing he rear tire every 5,000 miles.
