Newb with an exhaust/tune question??

[Bearly Legal]

Hey guys, Just got my 07 12R about 2 weeks ago. I bought it from Bergen Harley in NJ. its yellow with around 10k on it, if possibly the previous owner is on here. The bike has a Jardine slip on, and zero gravity wind screen. Other than that it appears stock. Its my first bike and runs really good but, at an idle in 1st gear, the bike seems to stutter a bit. like it has a miss in it? While tinkering with it the other day, my buddy and I took the Jardine pipe off and ran it open header. it actually sounds really good, like a typical Harley, and the stutter at idle in first is gone?! I am semi-mechanically inclined but work on cars. This is my first bike so there are some things im just unsure of and surely dont want to hurt the bike. Did the P.O. possibly tune the bike, or not tune it for the Jardine pipe? does it need to be tuned for it? Any body have any ideas or advice for me? Thanks in advance for any input.

 

[jcrosby4288]

i was thinking of buying that bike went and looked at it

 

[c818919]

You need to get ecm spy and look at the fuel maps to tell