I've searched and re-read everything I can find for the A6 cam on a d15.
Is this what they mean by needing to advance the gear by half a tooth (4.75*)?
I've never had something with adjustable cam of any sort and I don't want to screw it up.
The Definitive D15B7 / A6 / ZC Cam Post

 

Right now your AEM cam gear is not advanced or retarded and as you can see your lines are off by a few degrees. You turn the outside or inside ring until the lines are almost to the 5A then tighten the bolts down, that will be 4.75 Advanced. And then the outer lines on the outer ring will match the head (your red line).

It's been some time but I thought there was a specific year or years of A6 that didn't have the half tooth off while other years did..... I could be mistaken. It looks like you don't have the convenient year(s) A6 cam.