Does anyone have a definitive answer on this subject? I posted a question a while ago but both sides make very good points. I went to where I bought my bike and there it seems to all come down to money even though he suggested a slip because the carbs still needed to be jetted. It comes down to either a muzzy or a Yosh. (leaning more towards the Yosh.) I have a 01 ZX6-R still don't have a clue as to which one gives the best performance (slipon or full system). I am definetly looking for better performance over sound though but do not want to loose anything (mid-low range) either. Can anyone help me here?