I run a full Akra with shorty can / BMC race filter/ removed IAS system and the Ivans jet kit installed exactly as per instructions and it pulls hard all the way through the RPM range with no flatspots or dips at all. I'm neither rich or lean. I would suggest going back to the stock box. I think it helps if your elevation is close to sea level where Ivan because that is and where the kit was developed. I do have a spare airbox if anyone is in need.