David Menche wrote 
Hello:  I'd like to know of experiences with a ECU power chip for the 2.1
Digifant vanagons.  I have heard about these, what is the lists experience
with them?
  Specifically what is gained, and lost by using them.
On the same subject, what will a power chip add to a 2.1 liter with bigger
valves (ie Boston Engine stage III engine)?

Dave 
The Ozzy power chip I have tested lost 4 HP on the chassis dyno. This was a full throttle
power run the chip made the fuel mixture go lean off the scale as the rpm went up The only time I have seen any power gain from the ECU was when I used the European Dijijet ECU on my big valve engine I gained 13 HP on the Chassis dyno
I have a limited number of  european ECU's am selling them only with my big valve engines

Dave also wrote 
  Also I have read of problems of mixture being too rich with the stock FI
and bigger valves (and I assume same for ratio rockers)  How does the power
chip address this?
 
Dave 
Changing the size of the valves does not affect the air fuel mixture and I think we can assume the same for the ratio rockers. The ratio rockers can't be used with anything but the OEM stock valves due to the design of all aftermarket valves. I also think it is a mistake to add ratio rockers to a waterboxer engine the intake guides are to short and prone to wear and the valve springs are not heavy enough 
Bob Donalds 
http://www.bostonengine.com