In all honesty, the basic function is to allow the forks to bleed off some air pressure on the smaller hits, yet on big hits to cancel this function... and use the trapped air to assist the fork springs to prevent bottoming out.
The tanks only really serve two purposes...
1. Return CLEAN air to the forks.
2. Return escaped OIL to the forks.
If you were to plumb your forks to your handlebars, you would be placing your "Tank" above the fork.... this is good for drainback!
The handle bars dont need to be air tight, just plugged enough to keep the dirt out.
This is my system: $100 on Ebay.
http://www.framebreakerracing.com/New_F ... _Info.html

For very little money, you could make a fixed orifice , free backflow unit that offers 90% of what the big dollar system offer.
Maybe even contact these guys, tell them you got their system, and just want extra valves cuz your a "Pro" racer.
http://www.tgtracing.com/
There is NO DOUBT in my mind that subtanks improve small bump feel, without sacrificing G-out, or big bump bottoming resistance.
I dont think its a complicated as the companies what you to believe it is however...
