What are these??? Why are they falling off???

[junior varsity]

I wouldn't worry about knocking them out, as they fall out on their own over the years. The addition of noise was not all that noticeable to me as it happened gradually over the years, however, hearing a 696 start inside the showroom with stock pipes, I'm always impressed with just how quite they are.

By comparison, my full systemed, pod filtered, fcr'd, open clutched beast is rackety as all hell (just the way I like it). There's exhaust-booming, intake-sucking, carb-chirping, and clutch-clacking sounds to go with the ringing of the fins. Its a symphony.

[suzyj]

If anyone needs some, I've got some spares.  $10 each, plus postage.

[junior varsity]

[ducpainter]

Can someone who took them off clarify whether or not the noise difference is noticeable?  Is it a good/bad sound.  If anything I think the pucks restrict air flow to the fins but I always thought they served some performance purpose.  If not, I'll have to knock them out; I guess.

On my 750 SS the ring when cold was very noticeable.

On the 900, which has oil jackets in the cylinders, not as much.

I didn't take any out. They removed themselves.

[Spck31]

Well, they are remarkably effective at getting their owners to ask WTF is going on. 

WTF is going on, mmmmm i've seen those things on DMF......
Very useful thread, i lost my first one yesterday: