It definitely could. I don't remember my AFV but I was running lean when I first bought my bike. I didn't but their exhaust, but bought their dongle and they sent me the tune for the k&n +jardine combo, and it pretty much nailed it (99.7 last time I checked). If it still doesn't feel right with the new tune, you could be having fuel delivery issues (see: fuel pump), but that's for another thread...