Balance pipe position

A few months ago my boss returned from a bike show with a supplement that was meant to be intended to go alongside 'tuning for speed'. It detailed some tests carried out on exhaust systems for Commandos. The long and the short of it was that their research was not for outright performance but for road use/ production bikes. They found the standard diameter pipes work best but with the balance pipe moved 18" down the pipes from the valve seat. Norton were approached with this info but were not interested and folded shortly after (hence the lack of interest I guess) Apparently they were up 3hp on the Dyno as well!

This seems to be concurrent with most modern bikes that have a collector box/ balance pipe right down under the bike.

How I understand it is that when calculating the tuned length of an exhaust the figure is often useably short so it is doubled. If the balance pipe was then placed at the original position then the rapid expansion would create the desired wave before reaching the silencers? Maybe not, I'm only making my first foray into understanding exhaust harmonics.

Has anyone here experimented with balance pipe relocation rather than removal? Obviously I looking at low-mid range power rather than top end.

Sorry if this post is a little vague. I did not get a proper chance to look at the supplement before my boss left

Interesting. Nortons said at the time that the balance pipe was mostly to meet noise tests - dumping the exhaust through 2 mufflers reduced the noise output

You'd have to have a careful look at what cam and mufflers they used in this test, since they have a considerable bearing on results - can't just assume this will bolt (weld) on to any old commando and gain 3 hp.

Nortons offered a siamese exhaust (2 into 1) in the early 1960s, and from road tests this was a considerable improvement on the standard 2 pipes - but only at higher revs. The join would have been about the 18" mark ? Or possibly a bit more. (anyone got one to measure ?).

Speaking of adjustable cam timing, Inters and Manxs have a vernier coupling(s), that lets the cam timing be adjusted + or - quite a few degrees. This allows setting for different exhausts in particular, where open pipe or meg or even muffler need different timings to give best results...

Dunstalls answer was big bore headers down to just past the normal 850 cross over, and then normal bore from then on. At the time he (they?) claimed they were the best answer for a street Commando.
I assume the Dunstall 2-1-2 system was later, as it sounds more like the modern systems?