I am by no means a mechanic but doesn't the hmf pipe and filter allow the machine to breath much more making it run leaner. The jetting however does just the opposite allowing more fuel to pass making the machine now run richer. They should somewhat cancel each other out. I understand that jetting can vary between each bike and so the results are not the same for all machines even if they are the same make and model. HMF reccomends turning the A/F, but after installation my bike idles perfect. There is no hesitation or engine stumble. I know most people are adjusting there mixture, but before you adjusted did it idle/run good or did it need to be adjusted so it would? All info is appreciated!