This is the type of engine used in either V1 or V2 rockets or maybe both.
If you started one of these up in your driveway, you would instantly be considered a "Doc Brown" by everyone in your community.
The bike is as cool as it gets, but the actual noise is not only way over the top loud (open headers in a closed garage loud), but not a particularly nice sound either. No matter what size engine, the pitch always is outside the realm of what would be considered acceptable.
Love the bike, though.