On the VW they project in about as far but are not getting hit with the injector spray. If it is any problem I can plug that hole and set the glow plug off centered to the top; just have to mess with keeping the body indexed. I wish I had measured the actual compressed volume when I had the head off, to see what my compression ratio really is. I perhaps could stand to reduce the volume of the dish in the plug as well. That would be easy to fill with weld and simply re drill the last 1/4" or so. That would hide a bit more of the plug end.