If it makes you feel any better I have the 2008 RoadStar 1700S
and around 600 miles I was stuck in road constrution traffic and when we began to crawl She took to a low end knock, not the little knock it does like 1st. gear is to tall, but like a Mac truck. It was about 87 deg. and on new asphault. Went straight to the store and got a new filter and some 20-50 valvoline. Does not go away completely. Dealer looked at it and said the same as everyone else, nature of the beast. Could have been my imagination that day, but thought I had a drop in power, however I thought I had a problem. The Bike has been great though, I have to ride my other once in a while though.
It does tick in front exhaust area, who knows why??? and when you are stopped you can hear a tick in exhaust tail pipe area, just need louder exhaust. Looking at
Yami filter, don't know how it could get any flow, good looking filter though, I have never seen one that restrictive.
Any way I got just over 1,000 miles and it seems normal now. My c50 makes all its own noises also.