I have been running the TBM system with the shortest cone with a Concord 13/17 and I thought it worked pretty good until I installed a -3mm Skat Swirl 12/17. The Skat made a noticeable difference in initial hook up and the pump stayed loaded much better all the time. I lost a little top end, but who cares if the low-mid gains are that good. This setup does seem to load the engine a little more, but well worth it IMO. Best change I have made in a while.