I have been looking around here to see what people have to say about the use of the gytr header and the fuel requirements. I have read on some sites that the header can increase up to 20% with the use of the slip-on but there is no mention of needing a fuel controller. My bike is stock except for a K&N filter. I am gonna drop by the yamaha dealer tomorrow to see what they have to say about the header but thought I would ask around so see if a fuel controller is needed with the use of a header and a filter. I'm still gonna do a little searching to see if there is any gains with just the header without a slip-on. Maybe its not worth the upgrade.