Hey folks, Im looking for anyone that has had a FAA field approval for a smoke system on a Waco YMF-5 (C or D) model. Im looking at the smokingairplanes.com 3.5 gallon tank system. My A&P spoke with the local FSDO and they said it would be way quicker to just go off of a pre-existing approved 337 than try and start from scratch....just wondered if anyone has gone through this process or know someone that has. Thanks!