Ive had the heavy breather on my bike for over a year now and ive always kept the rainsock on. My tuner said it wouldnt restrict airflow so i just kept it on there. I just finished installing my lowers and took the filter off to give me more room to work. So i pull the rain sock off and notice the paper elemnt is brand spankin new. I thought to myself wow thats odd. So i held my hand on the outside of the sock and blew some light compressed air inside and i definetly noticed a restricted flow. I also blew with my mouth and little to no air came out. Aside from that test the filter element being so clean leads me to believe not much air is gettin through that sock. Took it off and now its in my bag awaiting a rainy ride.

 

Also the sock tends to sag. this happen to anyone else?

 

Haven't noticed mine "sagging", and I've ridden both with it on and off, and honestly can't say that I notice any difference in performance at all. Not to mention that if I get caught in an unexpected rain having to remember to pull over and put it on, which I have forgotten to do once or twice.

 

My elastic stretched out on mine,causing it to sag a little.The wife took it up a little in the back.I've ran mine for almost 26k mi.,had the sock on when it was dynoed.Didn't see any restriction whatsoever.Just clean it out once in awhile.I see very little dirt in the filter when I clean it.Intake looks like it came out of the box.I'll probably pick up another sock this spring,they're only $15.00

 

Gotta leave the sock on for show off the "Eagle beak". ;-)
I have plenty of dyno paper with the sock on and off. No difference here.

 

The rain sock itself acts as a filter catching larger debris so the element will be cleaner if you leave it on. I have a hard time believing that it makes no difference in air flow, it may not be noticeable but there has got to be some restriction with the rain sock on.

 

Bikes consume such a low volume of air and with the size of the filter being used I don't think that sock will make any difference as far as air consumption and performance are concerned.

 

I think my Cross Bones runs better with the rain sock removed. Perhaps it's in my head?

 

 

Could the sock on your bike just be clogged with dirt?

You indicated it had been on your bike for a year. I'd compare a new/clean sock to your used one and see if there was any difference in air flow.