I'm a new rider, so new in fact, that I am not quite sure how to ask the question. I've had my 2009 Sporster since April/May (maybe). I've been spending a ton of money on it trying to get it to the point of where I am comfortable on it. It sputters, drags, coughs, hesitates etc. I took it to HD and they told me I have an aftermarket air filter on it (what do I know...? I bought the bike off the floor). Anyway, they told me that the aftermarket filter is causing it to run lean and told me it needed some "adjustment" to the tune of $150 with no guarantee that it would solve the problem. I'll bite...what will? Higher octane...? Going back to the original type of air filter? I'm looking at the Screamin' Eagle Stage I but have no idea what I am doing and just trusting the guys at the dealership. HELP!