Yeah, I ran into that. B6/B7 4s have the issue as well. I thought it was shock length but it was not.
If it is shock length another option is to have the bottom mount shortened like this guy did
http://forums.quattroworld.com/a8/msgs/36807.phtml
Another example from soeone using UAS bags:
So long as the welds are good you'll be fine with this.