Trinity valves work very similar to the Rotax Rave valves. However, they use a keihin jet to bleed off pressure from the bellow. Smaller jet bleeds less, so you get a slower operation of the valve. Larger jet bleeds off pressure and makes the valve react vaster. It's not a bad set up. I fiddled with a 421 cheetah and it was actually pretty easy to get the valves dialed in for a buddy. I've got a 535 on the way now, so I'll see how it goes a second time around.