Want to upgrade to a STEREO intercom - the Optional Equipment List shown for the Maule's today don't include a stereo intercom that can be installed in a round dial hole like I want - only a Mono PSEngineering.

The SigTronics intercom is a cheap TSO intercom - shouldn't we be able to install this TSO intercom with a minor alteration entry from my A&P/IA?

(Please don't go down the rabbit whole of quality/features/comparisons, I'm really wanting to focus this convo on the legality of installing the TSO part via a minor alteration).

-Brendan

Since nobody wanted to answer this: Yes.