thanks for the comments chaps,
the reality is that last winter I hade to repair my 30 year old stainless Jota pipes, because the inlet stubs had worn thin and there was (consequently) some cracking, my son welded on some new stubs, but as I took all six components of the exhaust for only the second re-polishing of their lives, I remembered that in order to make things fit originally, I had to have 25mm of oval tube welded into the centre portion of the header to get things right in the first place, the trouble is/was all parts were previously used on other bikes, so I have no idea who made what, the pipes were bought used and separately so was the collector, then a very lucky stroke as Ralph the fungus faced supplier of the very last one of every single Laverda part in the book, was repairing a crash damaged bike and gave me a very slightly scratched silencer, and then inspected the left side which was also similar and said "you had better have both of those then" so I have no knowledge of who made what, no surprise that the fit wasn't too good. With the freshly modded in let stubs now fitted I was very careful to be sure that I had chain clearance on the right hand side and footy pedal clearance on the left hand side (standard pegs and levers), this made the left silencer have two welds from front of silencer to collector, and all now fits and hangs very nicely left and right,
funny thing is though, I just stood at the back of the bike and I think they are not level!, maybe I am paranoid (it was on the side stand)
anyway the main thing is that it all sits there unstressed and happy, no fowling, no problems, but the best thing is .... I cant see it when I am riding!
and for me every time, install three pipes and collector all in one go, but barely nipped on the collector clamps.
Coxy installs three pipes then plugs the collector onto the pipes, which suits him, and when he was prototyping he did that zillions of times, and in several different locations, including on the floor in Slaters showroom, his own workshop, the tube benders floor and even outside any of those places but inside the back of his van, each to their own, I guess, but as I said this is my way (queue frank Sinatra0
CLEM