Just a brief examination of the SI shows this:
At the engine level, an EIS may be installed replacing one or both of the engine’s traditional magnetos as a
minor alteration documented with an engine logbook entry. Current FAA guidance is that the required
airframe electrical system alterations needed for a single EIS installation may be accomplished by either minor
or major alteration. The installer can decide which type of alteration is best for their application. Lycoming
is providing the following recommendations based on this guidance:
1. If the installer considers the airframe alteration a minor alteration, this Service Instruction, FAA Advisory
Circular 43.13-1B and 2B, and other Advisory Circulars or applicable information can be referenced in
the airframe logbook as acceptable data.
2. If the installer considers the airframe alteration a major alteration requiring an FAA Form 337, this Service
Instruction, specific sections, chapters, and paragraphs used from FAA Advisory Circular 43.13-1B and
2B, and other approved instructions can be referenced in Block 8 of the Form 337 as approved data along
with the appropriate airframe logbook entry. If the installer does not have sufficient approved data to
substantiate the alteration, they should obtain approval of their acceptable data by an Aviation Safety
Inspector (field approval) or appropriately rated Designated Engineering Representative
https://www.lycoming.com/sites/default/files/SI1569B-Installation_Operation_and_Maintenance_of_Lycoming_EIS.pdf
I would like to see chapter and verse from the FAA, not from Lycoming... But from what they are saying, it sounds like they believe it could be done...
I just completed my Surefly installation paperwork and they didn't mention this possibility in their installation documentation... We filed the 337. I would have LOVED the E-Mag!