Very cool Tadd! They sell exhaust hose. Am still looking. I saved it some where but it was too small dia.
Vetus Denouden Rubber Exhaust Hose Rubber Exhaust Hose 3-1/2" - SLANG90 - BoatersWorld.com
Glad you brought this up again. I had to put a muffler on my HF and lost 5MPH. Thinking I can regain it useing "soft" pipe as a sort of expansion chamber. Com-on payday! lol
Funny thing about my 4 smoker, it ran and sounded great with just the header. Not a bit of pipe or muffler and no back pressure to speak of. Just a slight curve in the three inch long manifold. Loud but had a great sound.