my r75/6 had a balance pipe at 90 degrees to flow, at least 10inches long and very close to the front of the bike. find a front-view pic of a 1976 bmw r75/6, you'll find it. somebody, somewhere reckoned there was an advantage.
edit: i just googled "motorcycle balance tube" - plenty of good reading, they seem to have a positive effect on v-twin and boxer performance.