On bikes its very easy to alter the final drive (down gear it) and as the speedometers normally run from the gearbox these days they will read all sorts of crap.
Who cares if it has gears? Its not what you ride but how you ride it. I don't snub any bike slower/less powerful than mine, only riders who buy a fast bike then put a race exhaust on to talk shit down the pub.
Its a mates VW Caddy pick up, I put the exhaust on myself it was fairly easy just a pain to take the old one off! Fitted a power commander too and seems to ride fine.