I own the Airsoft gi upgraded triggerbox, and I must say, it's pretty decent. Definetly not a zero trigger, but better than a stock trigger box. It's full metal with nice upgraded sears. It also has the capability of replacement parts, unlike a lot of zero triggers. Also, +1 for the pdi chamber. It is awesome. Before you buy any power upgrades I would start with that and a nice aeg barrel. But, like many say the more expensive the parts, generally the better they are.