i think mine has no add-on insert.
so it just has the original silver color fin at the opening.
will getting the gold fin give me higher pitch?
but according to the hks website.
it says it's just for visual effect.

 

Purple one sounds different than the gold and silver inserts (the gold and silver sound very similar, with the silver being a little more high pitched than the gold). The purple one sounds like air rushing through where as the others sound like a whistle.

 

If your BOV is all blacked inside, then your engine is running a bit rich. Try cleaning it up a bit, if you can dis-assemble the BOV and use a computer-dusting spray it may do the trick. Try cleaning it, make some adjustment on the BOV ****. If all fails then maybe give HKS a call. They would probably not be too happy if the reason ur BOV didn't sound right was because it was dirty.