I made one from an empty Coleman propane cylinder and some EMT for my trike that has an 8HP predator. It looks kind of dumb, but works great so far. It has a much quieter, thumpy tone instead of sounding like a lawn mower. I ended up having to drill out jets after putting it on, so I'm assuming it flows better than the original one. I lost the photos of when I made it when my old phone died but I can take more if anybody wants to see it.