I just put on my Hard Krome 2 1/2 inch classic straights, and naturally my C50 was running rich. The guy I bought them from suggested to talk to a local dealer about hooking it up to a yosh box to to lean it out a little bit. I did exactly that and it worked perfectly. Saving me hundreds of $$. I was charged an hour labor while I waited and my bike runs great. It ran fine before but my riding partners could tell by the smell that it was on the rich side. So- my guess is that if you have a FI Bouldevard, and add aftermarkets, see if your dealer has a yosh box for FI bikes. I am not sure if this will work with the carb version or not.