I have searched and searched. I remember a long time ago reading in a thread that running 100:1 changes the air/fuel ratio. I can't remember if it made it leaner or richer. Can anyone help me? My fuel to air ratio was perfect with the clip on the very top notch and with the sbp chamber. Then I put my stock pipe on and it is running rich. I am going to buy a smaller jet from SBP but I was wondering if the Opti-2 is why it is running rich.