I've been fiddling with pneumatic engines for a while now and started to want to push my engine to its possible limits. I'll be running it at higher PSI ratings, my goal is at least 60 PSI, so I'll need to upgrade the tubing (I'm using cheap silicone tubing for the time being). I've seen rigid tubing before in builds such as LPEpower's V8 http://www.lpepower.com/products/pushrod-v8-engine. Does anyone by any chance know where to purchase rigid pneumatic tubing?