Advice on 'Commando' exhaust crack

Thanks so much for the replies. I can certainly see why the natural inclination is for the balance pipe system to crack at the welds. The stresses there when the engine is running must be huge. It therefore seems sensible for me to go with two single pipes so I don't face cracking two years from now with a balance pipe system.
Just out or curiosity: has anyone every used a flexible piece for the balance pipe? That would surely eliminate the stresses. If this seems like a good idea, anyone know where I could get such a piece?

I bought a dommie some years back, that had an exhaust system cobbled together with a flexible balance pipe.
Don't where it came from of course.
(And dommies didn't actually ever come with a balance pipe, think there was some Triumph influence somewhere in there.
Dommie spares were hard to get, at one stage).

When you think about it though, the pipes into the head are fairly rigidly fixed in a defined space, but joggle about with Commando isolastics,
and its the other end near the muffler tips that are more or less fixed that are forcing the flexing of the whole system,
so a flexible balance pipe isn't going to help much ?

Its the pipes being flexed in the weak spot/link near the head -where the balance pipes are joined in - that is being flexed and broken.
The mufflers really need (much) more flexible mountings, to take the stress off the whole system,
so the WHOLE exhaust system can joggle about without being flexed/stressed ??

Good point, but surely a flexible pipe would help with the vibration caused by the alternate firing of the two cylinders, wouldn't it?

The whole engine / gearbox / exhaust headers joggle about as one unit.
I'm not sure what a flexible balance pipe would actually allow to move independently.
Or whether such movement could even be helpful, or would be more destructive. ?
Fretting the header pipe nuts against their threads in the head is also a not uncommon problem...

Its having the muffler ends more or less fixed, and the header pipes allowed to joggle around that is flexing and breaking pipes,
at their weakest point = In balanced systems, where the balance pipe is welded in.