I am going for a stage one with the Super Tuner Pro (getting this one in case I do more serious tuning in the future), and the AC I have not chosen yet. I have an opportunity to get a pair of used screaming Eagle Slip-ons for my 2009 Fat Bob relatively cheep in good condition. I really like the way they look. I am fine that they are not much louder than stock. My question to you pro's (I'm new) is how is the performance gain with these mufflers compared to other slip-ons such as Rush mufflers with this setup. Again, not concerned with sound just performance gain.