Rich,

My ram air ducts do not vary much from the instructions from Jabiru USA.  I glued in little dams over the front two cylinders that are about 3/8" high.  The most I did was to vary the very front of the ducts where they cover cylinders #1 and #2.  I think I had to build up the height of right side and reduced the left side height based on actual flight test CHT data.  I see you have the newer style of engine, as opposed to the initial solid lifter and initial fin design.  That is a plus as I heard guys with the old design had more CHT issues than poeple with later engines.  Unless Jabiru USA has any new instructions, for first flights I would just put the little dams over the front two cylinders and fly.  Initial flight tests will have warm CHT's and after the first 25 hours, they will taper down to nice levels.  Your first ground runs will have the engine CHT's warm up real quick and might concern you about being able to make it to the end of the runway for your first flight.  Just keep these first taxi tests short and observe the limits.  It will get better as you break the engine in.  My first 25 hours were in warm summer temps and I never had to cut a flight short due to CHT levels.  I recall, at around hour 20 or so, making a full power climb from ground (910 MSL) to 10,000 MSL with no power reductions due to CHT concerns.

Good luck,

Dave