Bear in mind I did have a shroud around the supertrapp....not sure how many people ever noticed...but the whole supertrapp is covered in a sleeve with about 1/2" clearance all around....to direct the sound out the back. It was failing the sound check without it. It probably offered a bit of restriction to the exhaust.
And it's only enough for SMALL Allison airplane engine.
JohnnyB
And it's only enough for SMALL Allison airplane engine.
JohnnyB