1. Poor quality control from BMC
The first filter I got I returned for another because it looks like someone has carved it with a knife. There were still plastic shavings stuck to the filter. The second filter I received was no better. You can tell someone processed these things by hand at some point and they are not pretty. I cant speak for if this affects the quality of filtration. Make sure to clean the plastic trimmings off your filter so they dont end up blowing your engine. I did not notice any difference in sound or butt dyno after installing this. I have a slip on SC Project but no tune on my 21 ZX-6R