I have owned a 2005 FLSTCI for about a month or two now and all the work was done prior to me owning it. Aftermarket breather (i believe its the one you buy from HD) rush 3 inch slip ons and according to the dealer the software download has been done as well. My ears may just be hearing things but when i get on the throttle around the 50-60 mph, most noticeable around freeway lane walls or inside a tunnel or overpass i hear a whistle/squeal noise. It almost sounds like a turbo spooling up. While the sound is pretty cool, im almost certain its a sound of inefficiency from somewhere. I made sure the head pipes were tight, and ensured the clamps going to the slip ons were tight. am I looking in the wrong area? or am i maybe just hearing things... Thanks.

 

Stage 1 air intakes will sometimes whistle during acceleration. Also wind hitting the bike at speed will cause whistle noise on some models.

 

I've had my Rush for 8yrs and believe it or not.. it could be the pipes...

its been posted in here several time and I, can hear it at certain times.. usually its on Cement roads.. don't ask why,, they just do it.....

I have the Slash down pipes and I read its from bounce back off the road..

once your quit listening for it ,, it'll go away.....