L'il Villiers

[33d6]

I think the high pipes with Excelsior was just a matter of making your 9D powered bike look a little different from the rest. So many makers took up the 9D they all tended to look the same so a maker had to do something to stand out. It had nothing to do with competition, Excelsior had the Manxman for that.
 Wolf also fitted high pipes but Wolf never had the same exposure as did Excelsior.
So far I can list Coventry Eagle, Montgomery, Wolf, Excelsior, Carlton, Chell and of course  Francis Barnett and James as making 9D powered bikes without listing the Continental users.

Nevertheless, a private entry 9D powered Excelsior did earn a bronze medal in the 1938 ISDT so they were willing beastie if you pushed.

[R]

It had nothing to do with competition,

It never actually occurred to me they might be used for competition.
If someone won a medal in the ISDT, then I'm in awe !!

[cardan]

However, the 1939 Excelsior brochure shows high level exhausts as std fittings on the 125cc Universal, 
so you'd expect the Waratah here to be the same ...

I have a pretty poor illustration of a 125cc (8D presumably) Waratah in December 1937 and it certainly has high level pipes like the GO Universal Excelsior.

I've emailed the auctioneer re engine/frame numbers for the Waratah.

Leon