I will be getting my Barker Exhaust soon...probably tomorrow. I was wondering how big the difference will be in power after installing the quiet core. I ask because I am going to dyno tune the bike and I was wondering if it will screw the tune up if I go back and forth or should I keep it one way. I just do not always ride in areas that I need to keep the noise down. If the power difference is negligible, I will not worry about it. I know these bikes do not make huge numbers, so losing 3 or 4 horse power is a big deal. Thanks in advance.