Just another FYI, I'll bet there are a bunch of you out there flying in the IFR environment using GPS that do not have the required documentation from the local FSDO.  You cannot fly legally without this paperwork, and also includes a POH suplement.  I give WINGS seminars on this subject all over the Mountain states, and can elaborate more if there is interest. 

Ron,

 

I have such documentation and a POH supplement because I had the 430 installed by an actual avionics shop before Garmin would sell direct to a builder and the shop wouldn't release my airplane until the FSDO signed off on the installation.  I did have a little discussion with the FSDO about why I couldn't use my RMI micro-encoder as the altitude source for the GPS - even though it met TSO specs, it was not TSO'd. I had to buy an inferior TSO'd unit.  FSDO could never explain the difference and I had to succumb to the interpretations of a functionary to get the signoff rather than continue to tilt his windmill.

 

However, I thought the FSDO doc rule was rescinded a year or two ago?  Anyone at a famous Lancair avionics shop care to comment?