My friend just bought a Mazda 6 2.3l and decided to throw an AEM intake on there. When we got the instructions it was pretty clear they were for the '03 .. even though it was being sold as compatible with the '06. The installation went fairly painlessly... except I had to adapt the vacuum thing that plugs into the aem intake... no biggie. But there is no where to hook the intake vacuum solenoid back up to? Are you really supposed to leave it just hanging there not connected to anything but the electrical? That's what we did. After about a week the CEL came on. We did cover the one nipple with the cap... and are going to check right now if it is still in place. What does that vacuum solenoid do? Should it be hooked up to SOMETHING at least???