It will change your air/fuel mixture. If you only do a download (map), your looking at about $150 at the HD. If you have already added a tuner and done a Dino, you will have to do another synonymous.
Mike Hutchings Broken Bow, Ok.
2012 Street Glide
SE - Ventilator AC, 255 Cams, Race Tuner
V&H - Power Duals, Hi-Output Slip-Ons