Please don’t take this as gospel.
This spring I took my intake off with throttle body and cleaned thoroughly. I had quite a bit of carbon stuck to the underside of the throttle body and intake. I also had been running without any filter for the winter as I was having issues with the filter material freezing. I was using a standard barrel with burlap in place for the summer/spring before that.
After cleaning the intake/throttle body I also remodeled my filter. I made two concentric circles that I then wrapped with material. I wrapped both circles with burlap in multiple layers. I was planning to wrap the inner layer with a dense foam but did not have it available at the time.
I have drove roughly 400kms since the change and have noticed that I was getting quite a bit of carbon at the throttle bodies again. In my current configuration I don’t think the burlap alone is a sufficient filter so I will go ahead and try the high density foam around the inner circle.