Actually they dont restrict flow at all
unless your going down to 1/4"NPT or smaller tubing.
AND NOW! you can use silicone! I found a place that has small sleeves that insert into the tubing and stiffen it up. It's still thinner than a barb so your stil getting better flow.
Also if anybody has been trying to get me, my HD has died and I'm waiting on my replacement. I'm at work now, but I'm just harder to reach...
If you really need something email me at
mike@theidealpc.com