Just sharing my experience. Of course , I have a pretty modified 930, so that could contribute as well.
But pretty easy to identify that the pipe was the issue. Put on the one from ebay, took it out on the track, 1.1Bar. Came in, pulled it off, put old GHL one back on - go back out - 1.0 bar.
Now I just run without anything - 1.0 Bar.