I did a couple searches but really didn't find an answer to this question. I have a 2006 ultra classic that I bought about 4 weeks ago. It has an Arlen Ness airfilter (so I assume that it has a stage 1 upgrade), and a 2 into 1 Thunderheader exhaust. The guy also gave me the Screaming Eagle race tuner with software. My goal is to run a little quieter since I commute about 250 miles a day round trip to work, and the sound is getting to me.

If I put a stock exhaust back on the bike, would I be harming the engine if I didn't remap the fuel? My plan is to go back to stock exhaust, sell the Thunderheader exhaust, and put that money towards some quieter slip-ons. Then only have to remap the fuel once.

 

Since I don't know a thing about race tuners I probably shouldn't respond. Since the guy gave you a race tuner it probably has that installed. Without remapping your bike probably won't run that well when you go back to stock exhaust. When going back to stock exhaust your bike probably needs the stock map in your ECM.
This is a good question for HOG DOC.

 

Thanks. I appreciate the info.