Garmin 300XL Data cards.

abripl wrote:
Dave,

Just about everything on experimentals is "builder" approved. You
install it and make an aircraft log book entry that it was correctly
installed and tested. The exception is the required periodic IFR tests
of pitot, transponder, etc. which has to be done by approved trained
persons. Join rec.aviation.homebuilt news group and learn.

The annual condition inspection must be done by an approved person
as well (either the holder of the repairman's certificate or an A&P).
In addition, anything that would constitute a major modification to
the aircraft requires FAA notification (though I've never heard of
the FAA actually acting on any of these notifications).