Any one have suggestions where I could find replacement "flaps" which are internal to my 4" Gill tru-hulls?
They appear to be servicable (replacable with (2) screws), but I wasn't getting any where on the Gill web sight

Thanks.

I have the Gill tips as well. I just purchased fiber reinforced rubber sheet from Grainger (I think, It was a while ago), and cut out my own flappers. They work fine.
Easy and cheap

Paul

Sweet. I was trying to figure a way to cut them from some extra exhaust hose left over from a couple years ago

Your way sounds much easier.
Thanks for the advice.
Uncle Ernie