A Question For The Tuners

I would say Daystate electronic guns . I’ve seen a medium power tune from the Delta tuning close to 2ci/bar for efficiency. The impact and Crown are certainly good but are not that efficient when cranked up in power. 
The valves in the FX are not balanced at all. They are a conventional valve that is laid out a bit differently. A balanced valve would have a balance port on the backside of the poppet at atmospheric pressure to make it open easier.